17:I[462708,["/_next/static/chunks/3yo3kiro3bmlp.js","/_next/static/chunks/3vr2wvd8f2efb.js","/_next/static/chunks/2vtmb68_vu-9t.js","/_next/static/chunks/2s8mt6_8wrpfo.js","/_next/static/chunks/3vkulz2i3l61y.js","/_next/static/chunks/1cqw2i1silz0i.js","/_next/static/chunks/14dbm3lm_t629.js","/_next/static/chunks/335_v2mb569ld.js","/_next/static/chunks/1jvnwmb7jnkpz.js","/_next/static/chunks/3cmavum774kjt.js","/_next/static/chunks/3th-0-a2xf9qs.js","/_next/static/chunks/0p0xpwde6kzmv.js","/_next/static/chunks/401-sxxnzbtf_.js","/_next/static/chunks/0wywtv698a1v0.js","/_next/static/chunks/2botzqwpnrzyj.js"],"ArticleReader"] 18:T76cc,## One-minute summary **Acute coronary syndrome (ACS)** is the clinical spectrum caused most often by acute coronary atherothrombosis after plaque rupture or erosion and includes **ST-elevation myocardial infarction (STEMI), non-ST-elevation myocardial infarction (NSTEMI), and unstable angina (UA)**. Modern care is built around five simultaneous priorities: **recognize ischemia, obtain/interpret a 12-lead ECG rapidly, use high-sensitivity cardiac troponin serially, start evidence-based antithrombotic/anti-ischemic therapy, and choose the correct revascularization strategy without delay**.[1–4] The 2025 ACC/AHA/ACEP/NAEMSP/SCAI ACS guideline emphasizes DAPT, radial access for PCI, intravascular imaging for PCI guidance, complete revascularization in appropriate multivessel disease, prompt revascularization in cardiogenic shock, intensive lipid lowering, and cardiac rehabilitation.[1,2] The 2023 ESC ACS guideline similarly integrates STEMI and NSTE-ACS in one pathway and stresses high-sensitivity troponin algorithms and time-sensitive invasive care.[3] ### Immediate priorities 1. **ABCs + monitor + IV access**; treat shock, malignant arrhythmia, pulmonary edema, or cardiac arrest first. 2. **12-lead ECG promptly** and repeat if symptoms continue or the first tracing is nondiagnostic. 3. **High-sensitivity troponin** with an assay-specific accelerated serial algorithm; do not use a single universal numeric cutoff across assays. 4. **Aspirin immediately** unless true contraindication. 5. Determine whether this is **STEMI/occlusion requiring immediate reperfusion** versus **NSTE-ACS requiring risk-stratified invasive management**. 6. Add a **P2Y12 inhibitor + parenteral anticoagulation** according to the reperfusion/invasive strategy and bleeding risk. 7. Start **high-intensity statin** and secondary prevention early. ★ **High-yield principle:** In suspected ACS, the ECG determines the urgent reperfusion pathway; troponin helps diagnose myocardial injury/infarction but should **not delay reperfusion** for a clear STEMI pattern with an appropriate clinical presentation. --- ## Definition and classification ACS describes acute myocardial ischemia caused predominantly by an unstable atherosclerotic coronary lesion and thrombosis. The 2025 U.S. guideline focuses mainly on **type 1 ACS**, where plaque disruption and coronary thrombosis are the mechanism.[1] | Syndrome | ECG pattern | Troponin | Core concept | |---|---|---|---| | STEMI | Persistent ST elevation or an accepted STEMI-equivalent/occlusion pattern in the right context | Usually rises, but may initially be normal | Acute coronary occlusion or near-occlusion requiring immediate reperfusion | | NSTEMI | No persistent ST elevation; may show ST depression, T-wave inversion, transient elevation, or a nondiagnostic ECG | Rise/fall with ≥1 value above assay-specific 99th percentile plus evidence of ischemia | Myocardial infarction without classic persistent ST elevation | | Unstable angina | No persistent ST elevation | No biomarker evidence meeting MI criteria | Ischemic symptoms without detectable acute myocardial necrosis; less common in the high-sensitivity troponin era | ### Myocardial injury is not automatically myocardial infarction Troponin elevation means **myocardial injury**, not necessarily ACS. MI requires acute myocardial injury plus evidence of ischemia. Important alternative causes include sepsis, tachyarrhythmia, myocarditis, pulmonary embolism, acute heart failure, severe anemia, renal disease with dynamic injury, and supply-demand mismatch (type 2 MI). --- ## Pathophysiology The usual sequence is: **lipid-rich atherosclerotic plaque → plaque rupture or endothelial erosion → platelet adhesion/activation → thrombin generation → fibrin-rich thrombus → abrupt reduction in coronary blood flow → myocardial ischemia → myocyte necrosis if ischemia persists.** Ischemia begins subendocardially because wall stress and perfusion vulnerability are highest there. With sustained complete occlusion, necrosis can progress toward the epicardium. Infarct size is influenced by occlusion duration, collateral supply, myocardial oxygen demand, ischemic preconditioning, reperfusion timing, and microvascular obstruction. ### STEMI vs NSTEMI is an ECG phenotype, not a complete anatomy report Some acute coronary occlusions do not produce classic ST elevation. Conversely, ST elevation can be caused by pericarditis, early repolarization, left ventricular aneurysm, Takotsubo syndrome, electrolyte disorders, and other mimics. Clinical reasoning and serial ECGs matter. --- ## Risk factors Major atherosclerotic risk factors include: - Age and family history of premature ASCVD - Cigarette smoking - Hypertension - Diabetes mellitus - Dyslipidemia - Chronic kidney disease - Obesity and physical inactivity - Established coronary, cerebrovascular, or peripheral arterial disease - Chronic inflammatory disease Additional precipitants or modifiers include cocaine/amphetamine exposure, severe emotional or physiologic stress, acute infection, anemia, uncontrolled hypertension, and perioperative stress. --- ## Clinical presentation ### Typical ischemic symptoms - Retrosternal pressure, heaviness, squeezing, burning, or tightness - Radiation to arm(s), shoulder, neck, jaw, back, or epigastrium - Dyspnea - Diaphoresis - Nausea/vomiting - Sense of impending doom - Symptoms provoked by exertion and persistent at rest in acute presentations ### Atypical or less obvious presentations Older adults, women, and patients with diabetes or CKD may present with: - Dyspnea without prominent pain - Weakness or fatigue - Syncope/presyncope - Nausea or epigastric discomfort - Acute heart failure - Confusion Do not dismiss ACS because pain is described as “burning,” “indigestion,” or is not left-sided. ### Red flags for immediate instability - Hypotension, cool extremities, altered mentation - Ongoing severe chest pain despite initial therapy - Ventricular tachycardia/fibrillation - High-grade AV block or severe bradycardia - Acute pulmonary edema - Mechanical complication murmur - Recurrent dynamic ST changes - Cardiac arrest --- ## Initial assessment: first 10 minutes ### Core workflow | Component | Assessment | Interpretation | Immediate action | Anticipate deterioration | |---|---|---|---|---| | Airway/Breathing | Work of breathing, SpO₂, lung exam | Pulmonary edema, hypoxemia, alternative diagnosis | Oxygen only when clinically indicated; ventilatory support if needed | Acute LV failure, respiratory fatigue | | Circulation | HR, BP, perfusion, pulses, JVP | Shock, RV infarction, mechanical complication, arrhythmia | Monitor, IV access, cautious fluids if appropriate, shock pathway | Cardiogenic shock, VT/VF, AV block | | ECG | 12-lead ECG; right/posterior leads when indicated | STEMI/occlusion, ischemia, alternate diagnosis | Activate reperfusion pathway when indicated | Dynamic evolution; repeat ECG | | Biomarkers | hs-cTn serially | Acute myocardial injury pattern | Use validated assay-specific algorithm | Early presenters may have initially normal value | | History | Onset, quality, duration, bleeding history, anticoagulants, PDE5 inhibitors, prior stroke/TIA, allergy | Determines differential and treatment safety | Do not delay reperfusion for exhaustive history | Bleeding, medication contraindications | #### ECG Obtain a 12-lead ECG as early as possible in suspected ACS. Repeat ECGs if symptoms persist or recur, and consider: - **Right-sided leads (especially V4R)** for inferior MI with possible RV involvement - **Posterior leads V7–V9** when posterior MI is suspected, e.g., ST depression V1–V3 with a compatible presentation #### High-sensitivity troponin Use the laboratory's validated **high-sensitivity cardiac troponin (hs-cTn)** assay and accelerated serial algorithm. ESC guidance supports 0/1-hour or 0/2-hour pathways with assay-specific thresholds.[3,4] Interpretation requires: - Absolute concentration relative to the assay's 99th percentile - Rise/fall (delta) - Time since symptom onset - Renal function and chronic structural heart disease - Clinical/ECG evidence of ischemia ⚠ **Common trap:** A chronically elevated troponin in CKD does not prove NSTEMI. Look for a dynamic change and ischemic context. --- ### Differential diagnosis of acute chest pain | Diagnosis | Clues favoring diagnosis | Distinguishing test/findings | Immediate hazard | |---|---|---|---| | ACS | Pressure, diaphoresis, dynamic ECG/troponin | Serial ECG + hs-cTn | Arrhythmia, infarction, shock | | Aortic dissection | Abrupt tearing pain, pulse/BP differential, neuro deficit | CT angiography/TEE | Rupture; anticoagulation can be catastrophic | | Pulmonary embolism | Pleuritic pain, dyspnea, tachycardia, VTE risk | CT pulmonary angiography or V/Q | Obstructive shock | | Pericarditis | Pleuritic/positional pain, diffuse ST elevation/PR depression | ECG, echo | Tamponade if effusion | | Myocarditis | Viral prodrome, variable ECG, troponin, noncoronary pattern | CMR, echo, selective biopsy | Ventricular arrhythmia/shock | | Tension pneumothorax | Sudden dyspnea, unilateral absent breath sounds, shock | Clinical diagnosis | Immediate death without decompression | | Esophageal rupture | Severe pain after vomiting, systemic toxicity | CT/esophagram | Mediastinitis/sepsis | | GI/musculoskeletal pain | Reproducible or meal-related features may occur | Diagnosis of exclusion in high-risk cases | Risk is missed ACS | ★ **Exam pearl:** Do not give antithrombotics reflexively to undifferentiated tearing chest pain before considering dissection. --- ## STEMI and acute coronary occlusion ### Primary PCI is preferred when timely Primary PCI is the preferred reperfusion strategy when it can be performed within an appropriate system delay. ESC guidance recommends primary PCI when achievable within **120 minutes from STEMI diagnosis**; if timely PCI cannot be achieved and symptom onset is within 12 hours with no contraindication, fibrinolysis is indicated, followed by immediate transfer to a PCI-capable center.[3,5] #### STEMI network principles - Activate the cath lab early. - EMS should preferentially transport to a PCI-capable center when system targets can be met. - Do not wait for troponin when the clinical/ECG diagnosis is clear. - After fibrinolysis, transfer to PCI capability even if symptoms improve. - Rescue PCI is required for failed fibrinolysis or ongoing instability/ischemia. #### Cardiogenic shock Prompt revascularization remains a **Class 1** principle in ACS-related cardiogenic shock.[1,2] Shock management requires a multidisciplinary approach: airway/ventilation when necessary, invasive hemodynamic assessment in selected cases, vasopressor/inotrope support, and mechanical circulatory support only in carefully selected patients because benefit and complications vary by device and phenotype. --- ## NSTE-ACS: risk-stratified invasive management NSTE-ACS includes NSTEMI and unstable angina. An invasive strategy is recommended for ACS, but timing depends on risk.[3] #### Very high-risk features: immediate invasive evaluation Examples include: - Hemodynamic instability/cardiogenic shock - Recurrent or refractory chest pain despite medical treatment - Life-threatening arrhythmia or cardiac arrest attributed to ischemia - Mechanical complication - Acute heart failure clearly driven by ongoing ischemia - Recurrent dynamic ST-segment changes, particularly intermittent ST elevation #### High-risk features Features supporting early/inpatient invasive care include confirmed NSTEMI, significant dynamic ST/T changes, and high clinical risk (e.g., elevated GRACE risk). ESC guidance states an early invasive strategy (<24 h) should be considered in high-risk NSTE-ACS.[3] #### GRACE risk score The GRACE score estimates mortality using age, heart rate, systolic BP, creatinine, Killip class, cardiac arrest, ST deviation, and biomarkers. It is useful for prognosis and invasive-timing decisions, but it does not replace clinical judgment. --- ## Acute pharmacotherapy ### STANDARD OF CARE #### Aspirin The 2025 ACC/AHA guideline dosing table recommends:[1] - **Loading:** **162–325 mg orally**, non-enteric coated; chew when possible for faster effect. - **Maintenance:** **75–100 mg orally daily**. Aspirin is generally continued long term unless contraindicated or a specific antithrombotic strategy modifies it. #### P2Y12 inhibitors For patients undergoing PCI, **ticagrelor or prasugrel is preferred over clopidogrel** when not contraindicated.[1,2] | Agent | Loading | Maintenance | Key cautions | |---|---:|---:|---| | Ticagrelor | 180 mg PO | 90 mg PO twice daily | Dyspnea, bleeding; keep aspirin maintenance ≤100 mg/day | | Prasugrel | 60 mg PO | 10 mg daily if ≥60 kg and <75 y; 5 mg daily if <60 kg or age ≥75 y with caution | **Contraindicated with prior stroke/TIA**; higher bleeding risk | | Clopidogrel | 300 or 600 mg PO without fibrinolysis | 75 mg daily | Variable response; used when potent agents unsuitable | | Clopidogrel with fibrinolysis | 300 mg if age ≤75 y; 75 mg initial dose if >75 y | 75 mg daily | Standard P2Y12 option with fibrinolysis | #### DAPT duration For ACS patients **without high bleeding risk**, aspirin plus an oral P2Y12 inhibitor for **at least 12 months** is the default.[1,2] Bleeding-reduction strategies include: - PPI in patients at GI bleeding risk - In selected patients tolerating ticagrelor-based DAPT after PCI, transition to ticagrelor monotherapy ≥1 month after PCI - If chronic oral anticoagulation is required, discontinue aspirin 1–4 weeks after PCI and continue a P2Y12 inhibitor (preferably clopidogrel) with anticoagulation, individualized to ischemic and bleeding risk.[2] #### Anticoagulation Parenteral anticoagulation is part of acute ACS management, selected according to strategy and renal function (e.g., UFH, enoxaparin, or bivalirudin in appropriate settings). Dosing should follow the local PCI/fibrinolysis protocol because the required dose depends on whether the patient is proceeding to PCI, has already received anticoagulant, renal function, and activated clotting time targets. #### Nitrates For ischemic discomfort or hypertensive pulmonary congestion, sublingual nitroglycerin is commonly used if hemodynamically appropriate. The 2025 guideline cautions against nitrates when: - SBP <90 mmHg or >30 mmHg below baseline - Suspected RV infarction - Recent PDE5 inhibitor exposure: approximately **12 h after avanafil, 24 h after sildenafil/vardenafil, 48 h after tadalafil**.[1] Nitrates improve symptoms; they are **not a substitute for reperfusion** and have not been shown to reduce mortality in modern ACS care. #### Analgesia Opioids are reserved for persistent severe pain despite other anti-ischemic therapy. The 2025 guideline notes morphine **2–4 mg IV**, repeat every 5–15 minutes if needed, with careful monitoring; opioids can delay absorption/effect of oral P2Y12 inhibitors.[1] #### Oxygen Do **not** use routine oxygen solely because ACS is suspected when oxygenation is adequate. Give supplemental oxygen for hypoxemia or respiratory distress and titrate according to the patient's condition and local protocol. #### Beta-blocker In ACS without contraindications, the 2025 guideline recommends **early oral beta-blocker initiation within 24 hours** to reduce reinfarction and ventricular arrhythmias.[1] Delay/avoid in cardiogenic shock, decompensated acute HF, severe bradycardia, high-grade AV block without pacing, or other contraindications. #### High-intensity statin High-intensity statin therapy is recommended for all ACS patients unless contraindicated.[2] Common high-intensity regimens include: - **Atorvastatin 40–80 mg daily** - **Rosuvastatin 20–40 mg daily** The 2025 guideline recommends adding a nonstatin lipid-lowering agent when LDL-C remains **≥70 mg/dL (≥1.8 mmol/L)** on maximally tolerated statin; adding a nonstatin is also reasonable at **55–69 mg/dL** in selected patients.[2] #### ACE inhibitor / ARB and mineralocorticoid receptor antagonist ACEi/ARB is indicated particularly in higher-risk ACS patients (e.g., LVEF ≤40%, hypertension, diabetes, or anterior STEMI). An MRA is indicated for LVEF ≤40% with HF symptoms and/or diabetes when renal function and potassium permit.[1] --- ## PCI and revascularization ### Access and imaging The 2025 guideline recommends **radial access over femoral access** for PCI in ACS to reduce bleeding, vascular complications, and death.[1,2] **Intravascular imaging-guided PCI** is now a **Class 1, Level A** recommendation in the 2025 U.S. guideline.[2] ### Complete revascularization For appropriate STEMI and NSTE-ACS patients with multivessel disease, a strategy of complete revascularization is recommended/strongly favored, with timing and method determined by anatomy, comorbidities, shock status, renal function, lesion complexity, and surgical candidacy.[1,2] ⚠ **Shock exception:** Immediate multivessel PCI in cardiogenic shock is not automatically beneficial; culprit-vessel revascularization remains the immediate priority in many cases, with staged treatment of nonculprit disease according to anatomy and stability. --- ## Complications ### Electrical - Ventricular tachycardia/fibrillation - Accelerated idioventricular rhythm after reperfusion - Sinus bradycardia - AV block, especially inferior MI - Atrial fibrillation Treat unstable arrhythmias according to ACLS while correcting ischemia, hypoxia, potassium, magnesium, and acid-base abnormalities. ### Mechanical — think days after MI, sudden collapse or new murmur | Complication | Typical clue | Hemodynamics / echo | Action | |---|---|---|---| | Papillary muscle rupture → acute MR | Sudden pulmonary edema, shock, new systolic murmur | Severe eccentric MR | Emergency surgery; stabilize with afterload reduction/mechanical support when appropriate | | Ventricular septal rupture | New harsh holosystolic murmur, shock | Left-to-right shunt | Urgent surgical/interventional consultation | | Free-wall rupture | Sudden PEA, tamponade | Pericardial blood/effusion | Emergency surgical management | | LV aneurysm/pseudoaneurysm | Persistent ST changes, HF/embolism | Structural abnormality on echo/CT/CMR | Specialist management; pseudoaneurysm has rupture risk | ### Pump failure - Acute LV failure/pulmonary edema - RV infarction with preload sensitivity - Cardiogenic shock #### RV infarction pearl Suspect with inferior MI, hypotension, elevated JVP, and clear lungs. Obtain right-sided leads. Avoid aggressive nitrates/diuresis if preload dependent; give cautious fluid only if clinically appropriate and reassess frequently. --- ## Special populations ### Older adults and frailty Do not withhold evidence-based ACS care based solely on age. Balance invasive benefit against frailty, cognition, bleeding risk, kidney disease, goals of care, and functional status. ### Chronic kidney disease - hs-cTn may be chronically elevated; rely on dynamic change and clinical context. - Adjust renally cleared drugs. - Minimize contrast burden while avoiding harmful delays in indicated revascularization. ### Patients requiring oral anticoagulation Triple therapy markedly increases bleeding. The 2025 guideline favors early aspirin discontinuation (1–4 weeks after PCI) with continuation of oral anticoagulation plus a P2Y12 inhibitor, usually clopidogrel, when long-term anticoagulation is required.[2] ### Prior stroke/TIA **Prasugrel is contraindicated.** Choose another P2Y12 inhibitor when indicated. ### Pregnancy ACS in pregnancy is uncommon and more likely to involve mechanisms such as spontaneous coronary artery dissection. Management requires a pregnancy-heart team; maternal stabilization and indicated reperfusion take priority, while medication and radiation choices are individualized. --- ## Secondary prevention after ACS ### Before discharge - Smoking cessation treatment - Blood pressure optimization - Diabetes management - High-intensity statin ± nonstatin therapy - Antiplatelet plan documented with duration and bleeding strategy - Echocardiographic assessment of LVEF when appropriate - Cardiac rehabilitation referral - Exercise, weight, diet, and adherence counseling - Review driving/work restrictions per jurisdiction The 2025 guideline recommends a fasting lipid panel **4–8 weeks** after starting or adjusting lipid-lowering therapy and recommends referral to cardiac rehabilitation before discharge.[2] #### Cardiac rehabilitation Cardiac rehabilitation reduces recurrent events, improves functional status and quality of life, and is a Class 1 component of contemporary ACS secondary prevention.[2] --- ## Current guideline changes and areas of nuance ### 2025 ACC/AHA/ACEP/NAEMSP/SCAI — major practical updates **STANDARD OF CARE** - DAPT remains foundational. - Ticagrelor/prasugrel preferred over clopidogrel for PCI when appropriate. - Default DAPT ~12 months when bleeding risk is not high. - Radial PCI access favored. - Intravascular imaging-guided PCI elevated to Class 1. - Complete revascularization emphasized. - High-intensity statin for all ACS. - More aggressive nonstatin lipid-lowering thresholds. - Cardiac rehab referral before discharge.[1,2] ### 2023 ESC vs 2025 U.S. guideline Both support rapid hs-cTn pathways, invasive management for high-risk ACS, potent antiplatelet therapy, radial access, and complete revascularization in appropriate patients. Important practical differences may arise in preferred P2Y12 timing, exact invasive-timing categories, local fibrinolysis systems, and antithrombotic de-escalation strategies. Follow the locally adopted guideline and cath-lab protocol. ### EMERGING EVIDENCE - Individualized antiplatelet de-escalation and monotherapy strategies continue to evolve. - Mechanical circulatory support for selected AMI cardiogenic shock remains an area of active patient-selection research. - Physiology- and imaging-guided complete revascularization strategies continue to be refined. ### EXPERIMENTAL / INVESTIGATIONAL No investigational therapy should replace timely reperfusion, guideline antithrombotic treatment, and secondary prevention outside a trial or specialist protocol. --- ## Acute management checklist ### Suspected ACS - [ ] ABCs; identify shock, pulmonary edema, arrhythmia, cardiac arrest - [ ] Cardiac monitor + defibrillator availability - [ ] IV access - [ ] 12-lead ECG promptly; repeat if nondiagnostic - [ ] Right/posterior leads if indicated - [ ] hs-cTn serial algorithm - [ ] CBC, electrolytes, creatinine, glucose; coagulation studies when relevant - [ ] Aspirin 162–325 mg chewed unless contraindicated - [ ] Determine STEMI/occlusion vs NSTE-ACS pathway - [ ] P2Y12 inhibitor based on strategy and bleeding risk - [ ] Parenteral anticoagulation based on strategy - [ ] Nitrate only if appropriate; check BP/RV infarct/PDE5 exposure - [ ] Oxygen only if indicated - [ ] High-intensity statin - [ ] Early beta-blocker if stable and no contraindication - [ ] Echocardiography for LV function/complications as indicated - [ ] Document DAPT duration and bleeding mitigation - [ ] Cardiac rehab + secondary prevention plan --- ## Diagnostic / management algorithm ```text Acute chest discomfort / dyspnea / ischemic equivalent ↓ ABCs + monitor + IV + 12-lead ECG + hs-cTn ↓ Persistent ST elevation / occlusion pattern with compatible syndrome? ├── YES → STEMI reperfusion pathway │ ├─ Primary PCI achievable within system target → PCI │ └─ PCI not achievable within ~120 min, onset ≤12 h, │ no contraindication → fibrinolysis + transfer to PCI center │ └── NO → NSTE-ACS pathway ↓ Serial hs-cTn + repeat ECG + risk assessment ↓ Very high risk / instability? → Immediate invasive strategy High risk? → Early/inpatient invasive strategy Low risk / ACS ruled out? → Evaluate alternative diagnosis / safe disposition At all stages: Aspirin + strategy-appropriate P2Y12 + anticoagulation + high-intensity statin Treat shock/arrhythmia/HF immediately; reassess continuously ``` --- ## Common pitfalls | Pitfall | Why it is dangerous | Better approach | |---|---|---| | Waiting for troponin before activating clear STEMI | Delays reperfusion | Treat ECG + clinical syndrome as time-critical | | Treating every troponin elevation as type 1 NSTEMI | Causes diagnostic anchoring/bleeding risk | Distinguish injury, type 1 MI, type 2 MI, myocarditis, PE, etc. | | One normal ECG ends the workup | ACS can be dynamic | Repeat ECG during symptoms and use posterior/right leads when indicated | | Routine oxygen in normoxemia | No benefit; potential harm | Give for hypoxemia/respiratory distress | | Nitrates in RV infarction or after PDE5 inhibitor | Severe hypotension | Check hemodynamics and medication history | | Prasugrel in prior stroke/TIA | Major bleeding risk | Use alternative P2Y12 agent | | Ignoring bleeding risk when planning DAPT | Preventable hemorrhage | Use PPI, shortened/modified strategies when appropriate | | Discharge without rehab/lipid plan | Misses high-value prevention | Document secondary prevention before discharge | --- ## Exam-focused review ### Foundation / Step 1 Know plaque rupture/erosion, platelet activation, thrombin/fibrin, subendocardial vulnerability, transmural progression, and the physiologic consequences of reduced coronary blood flow. ### Step 2 CK Priority questions usually ask: **What must happen next?** - STEMI ECG → reperfusion, not stress testing. - Ongoing ischemia with instability → invasive management. - Troponin rise/fall + ischemic evidence without ST elevation → NSTEMI. - Inferior MI + hypotension + clear lungs → consider RV infarction; obtain right-sided leads and avoid nitrates. - New murmur + shock days after MI → mechanical complication. ### Step 3 / Resident Add strategy details: reperfusion timing, fibrinolysis contraindications, antithrombotic selection, bleeding mitigation, shock phenotype, mechanical complications, secondary prevention. ### MRCP / ABIM / boards Expect nuance around: - Type 1 vs type 2 MI - Dynamic hs-cTn interpretation - GRACE risk - Antiplatelet contraindications - DAPT duration in bleeding risk / anticoagulation - Post-MI LV dysfunction therapy - Mechanical complications --- ## Original MCQs #### 1. A 61-year-old man has 90 minutes of crushing chest pain. ECG shows 3 mm ST elevation in V2–V5. Initial hs-cTn is within the reference range. What is the best next step? A. Repeat troponin in 3 hours before treatment B. Exercise stress testing C. Activate immediate reperfusion/primary PCI pathway D. CT coronary angiography first **Answer: C.** Early troponin can be normal. A diagnostic STEMI pattern with an appropriate syndrome requires immediate reperfusion; biomarkers must not delay treatment. #### 2. A patient with inferior STEMI becomes hypotensive after sublingual nitroglycerin. Lungs are clear and JVP is elevated. Best next diagnostic step? A. V4R right-sided ECG lead B. D-dimer C. CT pulmonary angiography D. Stress echocardiography **Answer: A.** The pattern strongly suggests RV infarction with preload dependence. #### 3. Which P2Y12 inhibitor is contraindicated in a patient with prior ischemic stroke? A. Clopidogrel B. Ticagrelor C. Prasugrel D. Cangrelor **Answer: C.** Prasugrel is contraindicated after prior stroke/TIA because of bleeding risk. #### 4. A stable ACS patient undergoes PCI and has no high bleeding risk. What is the contemporary default DAPT duration? A. 48 hours B. 1 month C. 6 weeks D. At least 12 months **Answer: D.** The 2025 ACC/AHA guideline uses at least 12 months as the default in patients without high bleeding risk. #### 5. A patient with NSTEMI has shock, ongoing ischemic pain, and recurrent VT despite initial therapy. What invasive strategy is appropriate? A. Outpatient angiography B. Immediate invasive evaluation C. Stress testing before angiography D. Coronary calcium score **Answer: B.** Very high-risk NSTE-ACS features require immediate invasive care. --- ## References 1. Rao SV, O'Donoghue ML, Ruel M, et al. **2025 ACC/AHA/ACEP/NAEMSP/SCAI Guideline for the Management of Patients With Acute Coronary Syndromes.** *J Am Coll Cardiol.* 2025;85(22):2135–2237. doi: **10.1016/j.jacc.2024.11.009**. https://www.jacc.org/doi/10.1016/j.jacc.2024.11.009 2. American College of Cardiology / American Heart Association. **Top Things to Know: 2025 Guideline for Acute Coronary Syndromes.** Updated February 27, 2025. https://professional.heart.org/en/science-news/2025-guideline-for-the-management-of-patients-with-acute-coronary-syndromes/top-things-to-know 3. Byrne RA, Rossello X, Coughlan JJ, et al. **2023 ESC Guidelines for the management of acute coronary syndromes.** *Eur Heart J.* 2023;44(38):3720–3826. doi: **10.1093/eurheartj/ehad191**. PMID: **37622654**. https://www.escardio.org/guidelines/clinical-practice-guidelines/all-esc-practice-guidelines/acute-coronary-syndromes/ 4. Thygesen K, Alpert JS, Jaffe AS, et al. **Fourth Universal Definition of Myocardial Infarction (2018).** *Circulation.* 2018;138:e618–e651. doi: 10.1161/CIR.0000000000000617. 5. European Society of Cardiology. **Essential Messages from the 2023 ESC Guidelines for the Management of Acute Coronary Syndromes.** 2023. https://www.escardio.org/ 6. Kumbhani DJ, Cibotti-Sun M, Moore MM. **2025 Acute Coronary Syndromes Guideline-at-a-Glance.** *J Am Coll Cardiol.* 2025;85(22):2128–2134. doi: **10.1016/j.jacc.2025.01.018**. 7. Bikdeli B, Ujueta F, Rashedi S, et al. **Antiplatelet and Anticoagulant Therapy in the 2025 ACC/AHA Guideline for Acute Coronary Syndromes: Key Recommendations.** *J Am Coll Cardiol.* 2025. doi: **10.1016/j.jacc.2025.04.002**. --- **Review trigger:** Re-review whenever ACC/AHA or ESC ACS guidance changes, or when major trials alter PCI strategy, cardiogenic-shock support, antiplatelet duration/de-escalation, or lipid-lowering recommendations.19:T76ec,## One-minute summary **Acute coronary syndrome (ACS)** is the clinical spectrum caused most often by acute coronary atherothrombosis after plaque rupture or erosion and includes **ST-elevation myocardial infarction (STEMI), non-ST-elevation myocardial infarction (NSTEMI), and unstable angina (UA)**. Modern care is built around five simultaneous priorities: **recognize ischemia, obtain/interpret a 12-lead ECG rapidly, use high-sensitivity cardiac troponin serially, start evidence-based antithrombotic/anti-ischemic therapy, and choose the correct revascularization strategy without delay**.[1–4] The 2025 ACC/AHA/ACEP/NAEMSP/SCAI ACS guideline emphasizes DAPT, radial access for PCI, intravascular imaging for PCI guidance, complete revascularization in appropriate multivessel disease, prompt revascularization in cardiogenic shock, intensive lipid lowering, and cardiac rehabilitation.[1,2] The 2023 ESC ACS guideline similarly integrates STEMI and NSTE-ACS in one pathway and stresses high-sensitivity troponin algorithms and time-sensitive invasive care.[3] ### Immediate priorities 1. **ABCs + monitor + IV access**; treat shock, malignant arrhythmia, pulmonary edema, or cardiac arrest first. 2. **12-lead ECG promptly** and repeat if symptoms continue or the first tracing is nondiagnostic. 3. **High-sensitivity troponin** with an assay-specific accelerated serial algorithm; do not use a single universal numeric cutoff across assays. 4. **Aspirin immediately** unless true contraindication. 5. Determine whether this is **STEMI/occlusion requiring immediate reperfusion** versus **NSTE-ACS requiring risk-stratified invasive management**. 6. Add a **P2Y12 inhibitor + parenteral anticoagulation** according to the reperfusion/invasive strategy and bleeding risk. 7. Start **high-intensity statin** and secondary prevention early. ★ **High-yield principle:** In suspected ACS, the ECG determines the urgent reperfusion pathway; troponin helps diagnose myocardial injury/infarction but should **not delay reperfusion** for a clear STEMI pattern with an appropriate clinical presentation. --- ## Definition and classification ACS describes acute myocardial ischemia caused predominantly by an unstable atherosclerotic coronary lesion and thrombosis. The 2025 U.S. guideline focuses mainly on **type 1 ACS**, where plaque disruption and coronary thrombosis are the mechanism.[1] | Syndrome | ECG pattern | Troponin | Core concept | |---|---|---|---| | STEMI | Persistent ST elevation or an accepted STEMI-equivalent/occlusion pattern in the right context | Usually rises, but may initially be normal | Acute coronary occlusion or near-occlusion requiring immediate reperfusion | | NSTEMI | No persistent ST elevation; may show ST depression, T-wave inversion, transient elevation, or a nondiagnostic ECG | Rise/fall with ≥1 value above assay-specific 99th percentile plus evidence of ischemia | Myocardial infarction without classic persistent ST elevation | | Unstable angina | No persistent ST elevation | No biomarker evidence meeting MI criteria | Ischemic symptoms without detectable acute myocardial necrosis; less common in the high-sensitivity troponin era | ### Myocardial injury is not automatically myocardial infarction Troponin elevation means **myocardial injury**, not necessarily ACS. MI requires acute myocardial injury plus evidence of ischemia. Important alternative causes include sepsis, tachyarrhythmia, myocarditis, pulmonary embolism, acute heart failure, severe anemia, renal disease with dynamic injury, and supply-demand mismatch (type 2 MI). --- ## Pathophysiology The usual sequence is: **lipid-rich atherosclerotic plaque → plaque rupture or endothelial erosion → platelet adhesion/activation → thrombin generation → fibrin-rich thrombus → abrupt reduction in coronary blood flow → myocardial ischemia → myocyte necrosis if ischemia persists.** Ischemia begins subendocardially because wall stress and perfusion vulnerability are highest there. With sustained complete occlusion, necrosis can progress toward the epicardium. Infarct size is influenced by occlusion duration, collateral supply, myocardial oxygen demand, ischemic preconditioning, reperfusion timing, and microvascular obstruction. ### STEMI vs NSTEMI is an ECG phenotype, not a complete anatomy report Some acute coronary occlusions do not produce classic ST elevation. Conversely, ST elevation can be caused by pericarditis, early repolarization, left ventricular aneurysm, Takotsubo syndrome, electrolyte disorders, and other mimics. Clinical reasoning and serial ECGs matter. --- ## Risk factors Major atherosclerotic risk factors include: - Age and family history of premature ASCVD - Cigarette smoking - Hypertension - Diabetes mellitus - Dyslipidemia - Chronic kidney disease - Obesity and physical inactivity - Established coronary, cerebrovascular, or peripheral arterial disease - Chronic inflammatory disease Additional precipitants or modifiers include cocaine/amphetamine exposure, severe emotional or physiologic stress, acute infection, anemia, uncontrolled hypertension, and perioperative stress. --- ## Clinical presentation ### Typical ischemic symptoms - Retrosternal pressure, heaviness, squeezing, burning, or tightness - Radiation to arm(s), shoulder, neck, jaw, back, or epigastrium - Dyspnea - Diaphoresis - Nausea/vomiting - Sense of impending doom - Symptoms provoked by exertion and persistent at rest in acute presentations ### Atypical or less obvious presentations Older adults, women, and patients with diabetes or CKD may present with: - Dyspnea without prominent pain - Weakness or fatigue - Syncope/presyncope - Nausea or epigastric discomfort - Acute heart failure - Confusion Do not dismiss ACS because pain is described as “burning,” “indigestion,” or is not left-sided. ### Red flags for immediate instability - Hypotension, cool extremities, altered mentation - Ongoing severe chest pain despite initial therapy - Ventricular tachycardia/fibrillation - High-grade AV block or severe bradycardia - Acute pulmonary edema - Mechanical complication murmur - Recurrent dynamic ST changes - Cardiac arrest --- ## Initial assessment: first 10 minutes ### Core workflow | Component | Assessment | Interpretation | Immediate action | Anticipate deterioration | |---|---|---|---|---| | Airway/Breathing | Work of breathing, SpO₂, lung exam | Pulmonary edema, hypoxemia, alternative diagnosis | Oxygen only when clinically indicated; ventilatory support if needed | Acute LV failure, respiratory fatigue | | Circulation | HR, BP, perfusion, pulses, JVP | Shock, RV infarction, mechanical complication, arrhythmia | Monitor, IV access, cautious fluids if appropriate, shock pathway | Cardiogenic shock, VT/VF, AV block | | ECG | 12-lead ECG; right/posterior leads when indicated | STEMI/occlusion, ischemia, alternate diagnosis | Activate reperfusion pathway when indicated | Dynamic evolution; repeat ECG | | Biomarkers | hs-cTn serially | Acute myocardial injury pattern | Use validated assay-specific algorithm | Early presenters may have initially normal value | | History | Onset, quality, duration, bleeding history, anticoagulants, PDE5 inhibitors, prior stroke/TIA, allergy | Determines differential and treatment safety | Do not delay reperfusion for exhaustive history | Bleeding, medication contraindications | #### ECG Obtain a 12-lead ECG as early as possible in suspected ACS. Repeat ECGs if symptoms persist or recur, and consider: - **Right-sided leads (especially V4R)** for inferior MI with possible RV involvement - **Posterior leads V7–V9** when posterior MI is suspected, e.g., ST depression V1–V3 with a compatible presentation #### High-sensitivity troponin Use the laboratory's validated **high-sensitivity cardiac troponin (hs-cTn)** assay and accelerated serial algorithm. ESC guidance supports 0/1-hour or 0/2-hour pathways with assay-specific thresholds.[3,4] Interpretation requires: - Absolute concentration relative to the assay's 99th percentile - Rise/fall (delta) - Time since symptom onset - Renal function and chronic structural heart disease - Clinical/ECG evidence of ischemia ⚠ **Common trap:** A chronically elevated troponin in CKD does not prove NSTEMI. Look for a dynamic change and ischemic context. --- ### Differential diagnosis of acute chest pain | Diagnosis | Clues favoring diagnosis | Distinguishing test/findings | Immediate hazard | |---|---|---|---| | ACS | Pressure, diaphoresis, dynamic ECG/troponin | Serial ECG + hs-cTn | Arrhythmia, infarction, shock | | Aortic dissection | Abrupt tearing pain, pulse/BP differential, neuro deficit | CT angiography/TEE | Rupture; anticoagulation can be catastrophic | | Pulmonary embolism | Pleuritic pain, dyspnea, tachycardia, VTE risk | CT pulmonary angiography or V/Q | Obstructive shock | | Pericarditis | Pleuritic/positional pain, diffuse ST elevation/PR depression | ECG, echo | Tamponade if effusion | | Myocarditis | Viral prodrome, variable ECG, troponin, noncoronary pattern | CMR, echo, selective biopsy | Ventricular arrhythmia/shock | | Tension pneumothorax | Sudden dyspnea, unilateral absent breath sounds, shock | Clinical diagnosis | Immediate death without decompression | | Esophageal rupture | Severe pain after vomiting, systemic toxicity | CT/esophagram | Mediastinitis/sepsis | | GI/musculoskeletal pain | Reproducible or meal-related features may occur | Diagnosis of exclusion in high-risk cases | Risk is missed ACS | ★ **Exam pearl:** Do not give antithrombotics reflexively to undifferentiated tearing chest pain before considering dissection. --- ## STEMI and acute coronary occlusion ### Primary PCI is preferred when timely Primary PCI is the preferred reperfusion strategy when it can be performed within an appropriate system delay. ESC guidance recommends primary PCI when achievable within **120 minutes from STEMI diagnosis**; if timely PCI cannot be achieved and symptom onset is within 12 hours with no contraindication, fibrinolysis is indicated, followed by immediate transfer to a PCI-capable center.[3,5] #### STEMI network principles - Activate the cath lab early. - EMS should preferentially transport to a PCI-capable center when system targets can be met. - Do not wait for troponin when the clinical/ECG diagnosis is clear. - After fibrinolysis, transfer to PCI capability even if symptoms improve. - Rescue PCI is required for failed fibrinolysis or ongoing instability/ischemia. #### Cardiogenic shock Prompt revascularization remains a **Class 1** principle in ACS-related cardiogenic shock.[1,2] Shock management requires a multidisciplinary approach: airway/ventilation when necessary, invasive hemodynamic assessment in selected cases, vasopressor/inotrope support, and mechanical circulatory support only in carefully selected patients because benefit and complications vary by device and phenotype. --- ## NSTE-ACS: risk-stratified invasive management NSTE-ACS includes NSTEMI and unstable angina. An invasive strategy is recommended for ACS, but timing depends on risk.[3] #### Very high-risk features: immediate invasive evaluation Examples include: - Hemodynamic instability/cardiogenic shock - Recurrent or refractory chest pain despite medical treatment - Life-threatening arrhythmia or cardiac arrest attributed to ischemia - Mechanical complication - Acute heart failure clearly driven by ongoing ischemia - Recurrent dynamic ST-segment changes, particularly intermittent ST elevation #### High-risk features Features supporting early/inpatient invasive care include confirmed NSTEMI, significant dynamic ST/T changes, and high clinical risk (e.g., elevated GRACE risk). ESC guidance states an early invasive strategy (<24 h) should be considered in high-risk NSTE-ACS.[3] #### GRACE risk score The GRACE score estimates mortality using age, heart rate, systolic BP, creatinine, Killip class, cardiac arrest, ST deviation, and biomarkers. It is useful for prognosis and invasive-timing decisions, but it does not replace clinical judgment. --- ## Acute pharmacotherapy ### STANDARD OF CARE #### Aspirin The 2025 ACC/AHA guideline dosing table recommends:[1] - **Loading:** **162–325 mg orally**, non-enteric coated; chew when possible for faster effect. - **Maintenance:** **75–100 mg orally daily**. Aspirin is generally continued long term unless contraindicated or a specific antithrombotic strategy modifies it. #### P2Y12 inhibitors For patients undergoing PCI, **ticagrelor or prasugrel is preferred over clopidogrel** when not contraindicated.[1,2] | Agent | Loading | Maintenance | Key cautions | |---|---:|---:|---| | Ticagrelor | 180 mg PO | 90 mg PO twice daily | Dyspnea, bleeding; keep aspirin maintenance ≤100 mg/day | | Prasugrel | 60 mg PO | 10 mg daily if ≥60 kg and <75 y; 5 mg daily if <60 kg or age ≥75 y with caution | **Contraindicated with prior stroke/TIA**; higher bleeding risk | | Clopidogrel | 300 or 600 mg PO without fibrinolysis | 75 mg daily | Variable response; used when potent agents unsuitable | | Clopidogrel with fibrinolysis | 300 mg if age ≤75 y; 75 mg initial dose if >75 y | 75 mg daily | Standard P2Y12 option with fibrinolysis | #### DAPT duration For ACS patients **without high bleeding risk**, aspirin plus an oral P2Y12 inhibitor for **at least 12 months** is the default.[1,2] Bleeding-reduction strategies include: - PPI in patients at GI bleeding risk - In selected patients tolerating ticagrelor-based DAPT after PCI, transition to ticagrelor monotherapy ≥1 month after PCI - If chronic oral anticoagulation is required, discontinue aspirin 1–4 weeks after PCI and continue a P2Y12 inhibitor (preferably clopidogrel) with anticoagulation, individualized to ischemic and bleeding risk.[2] #### Anticoagulation Parenteral anticoagulation is part of acute ACS management, selected according to strategy and renal function (e.g., UFH, enoxaparin, or bivalirudin in appropriate settings). Dosing should follow the local PCI/fibrinolysis protocol because the required dose depends on whether the patient is proceeding to PCI, has already received anticoagulant, renal function, and activated clotting time targets. #### Nitrates For ischemic discomfort or hypertensive pulmonary congestion, sublingual nitroglycerin is commonly used if hemodynamically appropriate. The 2025 guideline cautions against nitrates when: - SBP <90 mmHg or >30 mmHg below baseline - Suspected RV infarction - Recent PDE5 inhibitor exposure: approximately **12 h after avanafil, 24 h after sildenafil/vardenafil, 48 h after tadalafil**.[1] Nitrates improve symptoms; they are **not a substitute for reperfusion** and have not been shown to reduce mortality in modern ACS care. #### Analgesia Opioids are reserved for persistent severe pain despite other anti-ischemic therapy. The 2025 guideline notes morphine **2–4 mg IV**, repeat every 5–15 minutes if needed, with careful monitoring; opioids can delay absorption/effect of oral P2Y12 inhibitors.[1] #### Oxygen Do **not** use routine oxygen solely because ACS is suspected when oxygenation is adequate. Give supplemental oxygen for hypoxemia or respiratory distress and titrate according to the patient's condition and local protocol. #### Beta-blocker In ACS without contraindications, the 2025 guideline recommends **early oral beta-blocker initiation within 24 hours** to reduce reinfarction and ventricular arrhythmias.[1] Delay/avoid in cardiogenic shock, decompensated acute HF, severe bradycardia, high-grade AV block without pacing, or other contraindications. #### High-intensity statin High-intensity statin therapy is recommended for all ACS patients unless contraindicated.[2] Common high-intensity regimens include: - **Atorvastatin 40–80 mg daily** - **Rosuvastatin 20–40 mg daily** The 2025 guideline recommends adding a nonstatin lipid-lowering agent when LDL-C remains **≥70 mg/dL (≥1.8 mmol/L)** on maximally tolerated statin; adding a nonstatin is also reasonable at **55–69 mg/dL** in selected patients.[2] #### ACE inhibitor / ARB and mineralocorticoid receptor antagonist ACEi/ARB is indicated particularly in higher-risk ACS patients (e.g., LVEF ≤40%, hypertension, diabetes, or anterior STEMI). An MRA is indicated for LVEF ≤40% with HF symptoms and/or diabetes when renal function and potassium permit.[1] --- ## PCI and revascularization ### Access and imaging The 2025 guideline recommends **radial access over femoral access** for PCI in ACS to reduce bleeding, vascular complications, and death.[1,2] **Intravascular imaging-guided PCI** is now a **Class 1, Level A** recommendation in the 2025 U.S. guideline.[2] ### Complete revascularization For appropriate STEMI and NSTE-ACS patients with multivessel disease, a strategy of complete revascularization is recommended/strongly favored, with timing and method determined by anatomy, comorbidities, shock status, renal function, lesion complexity, and surgical candidacy.[1,2] ⚠ **Shock exception:** Immediate multivessel PCI in cardiogenic shock is not automatically beneficial; culprit-vessel revascularization remains the immediate priority in many cases, with staged treatment of nonculprit disease according to anatomy and stability. --- ## Complications ### Electrical - Ventricular tachycardia/fibrillation - Accelerated idioventricular rhythm after reperfusion - Sinus bradycardia - AV block, especially inferior MI - [Atrial fibrillation](/library/atrial-fibrillation) Treat unstable arrhythmias according to ACLS while correcting ischemia, hypoxia, potassium, magnesium, and acid-base abnormalities. ### Mechanical — think days after MI, sudden collapse or new murmur | Complication | Typical clue | Hemodynamics / echo | Action | |---|---|---|---| | Papillary muscle rupture → acute MR | Sudden pulmonary edema, shock, new systolic murmur | Severe eccentric MR | Emergency surgery; stabilize with afterload reduction/mechanical support when appropriate | | Ventricular septal rupture | New harsh holosystolic murmur, shock | Left-to-right shunt | Urgent surgical/interventional consultation | | Free-wall rupture | Sudden PEA, tamponade | Pericardial blood/effusion | Emergency surgical management | | LV aneurysm/pseudoaneurysm | Persistent ST changes, HF/embolism | Structural abnormality on echo/CT/CMR | Specialist management; pseudoaneurysm has rupture risk | ### Pump failure - Acute LV failure/pulmonary edema - RV infarction with preload sensitivity - Cardiogenic shock #### RV infarction pearl Suspect with inferior MI, hypotension, elevated JVP, and clear lungs. Obtain right-sided leads. Avoid aggressive nitrates/diuresis if preload dependent; give cautious fluid only if clinically appropriate and reassess frequently. --- ## Special populations ### Older adults and frailty Do not withhold evidence-based ACS care based solely on age. Balance invasive benefit against frailty, cognition, bleeding risk, kidney disease, goals of care, and functional status. ### Chronic kidney disease - hs-cTn may be chronically elevated; rely on dynamic change and clinical context. - Adjust renally cleared drugs. - Minimize contrast burden while avoiding harmful delays in indicated revascularization. ### Patients requiring oral anticoagulation Triple therapy markedly increases bleeding. The 2025 guideline favors early aspirin discontinuation (1–4 weeks after PCI) with continuation of oral anticoagulation plus a P2Y12 inhibitor, usually clopidogrel, when long-term anticoagulation is required.[2] ### Prior stroke/TIA **Prasugrel is contraindicated.** Choose another P2Y12 inhibitor when indicated. ### Pregnancy ACS in pregnancy is uncommon and more likely to involve mechanisms such as spontaneous coronary artery dissection. Management requires a pregnancy-heart team; maternal stabilization and indicated reperfusion take priority, while medication and radiation choices are individualized. --- ## Secondary prevention after ACS ### Before discharge - Smoking cessation treatment - Blood pressure optimization - Diabetes management - High-intensity statin ± nonstatin therapy - Antiplatelet plan documented with duration and bleeding strategy - Echocardiographic assessment of LVEF when appropriate - Cardiac rehabilitation referral - Exercise, weight, diet, and adherence counseling - Review driving/work restrictions per jurisdiction The 2025 guideline recommends a fasting lipid panel **4–8 weeks** after starting or adjusting lipid-lowering therapy and recommends referral to cardiac rehabilitation before discharge.[2] #### Cardiac rehabilitation Cardiac rehabilitation reduces recurrent events, improves functional status and quality of life, and is a Class 1 component of contemporary ACS secondary prevention.[2] --- ## Current guideline changes and areas of nuance ### 2025 ACC/AHA/ACEP/NAEMSP/SCAI — major practical updates **STANDARD OF CARE** - DAPT remains foundational. - Ticagrelor/prasugrel preferred over clopidogrel for PCI when appropriate. - Default DAPT ~12 months when bleeding risk is not high. - Radial PCI access favored. - Intravascular imaging-guided PCI elevated to Class 1. - Complete revascularization emphasized. - High-intensity statin for all ACS. - More aggressive nonstatin lipid-lowering thresholds. - Cardiac rehab referral before discharge.[1,2] ### 2023 ESC vs 2025 U.S. guideline Both support rapid hs-cTn pathways, invasive management for high-risk ACS, potent antiplatelet therapy, radial access, and complete revascularization in appropriate patients. Important practical differences may arise in preferred P2Y12 timing, exact invasive-timing categories, local fibrinolysis systems, and antithrombotic de-escalation strategies. Follow the locally adopted guideline and cath-lab protocol. ### EMERGING EVIDENCE - Individualized antiplatelet de-escalation and monotherapy strategies continue to evolve. - Mechanical circulatory support for selected AMI cardiogenic shock remains an area of active patient-selection research. - Physiology- and imaging-guided complete revascularization strategies continue to be refined. ### EXPERIMENTAL / INVESTIGATIONAL No investigational therapy should replace timely reperfusion, guideline antithrombotic treatment, and secondary prevention outside a trial or specialist protocol. --- ## Acute management checklist ### Suspected ACS - [ ] ABCs; identify shock, pulmonary edema, arrhythmia, cardiac arrest - [ ] Cardiac monitor + defibrillator availability - [ ] IV access - [ ] 12-lead ECG promptly; repeat if nondiagnostic - [ ] Right/posterior leads if indicated - [ ] hs-cTn serial algorithm - [ ] CBC, electrolytes, creatinine, glucose; coagulation studies when relevant - [ ] Aspirin 162–325 mg chewed unless contraindicated - [ ] Determine STEMI/occlusion vs NSTE-ACS pathway - [ ] P2Y12 inhibitor based on strategy and bleeding risk - [ ] Parenteral anticoagulation based on strategy - [ ] Nitrate only if appropriate; check BP/RV infarct/PDE5 exposure - [ ] Oxygen only if indicated - [ ] High-intensity statin - [ ] Early beta-blocker if stable and no contraindication - [ ] Echocardiography for LV function/complications as indicated - [ ] Document DAPT duration and bleeding mitigation - [ ] Cardiac rehab + secondary prevention plan --- ## Diagnostic / management algorithm ```text Acute chest discomfort / dyspnea / ischemic equivalent ↓ ABCs + monitor + IV + 12-lead ECG + hs-cTn ↓ Persistent ST elevation / occlusion pattern with compatible syndrome? ├── YES → STEMI reperfusion pathway │ ├─ Primary PCI achievable within system target → PCI │ └─ PCI not achievable within ~120 min, onset ≤12 h, │ no contraindication → fibrinolysis + transfer to PCI center │ └── NO → NSTE-ACS pathway ↓ Serial hs-cTn + repeat ECG + risk assessment ↓ Very high risk / instability? → Immediate invasive strategy High risk? → Early/inpatient invasive strategy Low risk / ACS ruled out? → Evaluate alternative diagnosis / safe disposition At all stages: Aspirin + strategy-appropriate P2Y12 + anticoagulation + high-intensity statin Treat shock/arrhythmia/HF immediately; reassess continuously ``` --- ## Common pitfalls | Pitfall | Why it is dangerous | Better approach | |---|---|---| | Waiting for troponin before activating clear STEMI | Delays reperfusion | Treat ECG + clinical syndrome as time-critical | | Treating every troponin elevation as type 1 NSTEMI | Causes diagnostic anchoring/bleeding risk | Distinguish injury, type 1 MI, type 2 MI, myocarditis, PE, etc. | | One normal ECG ends the workup | ACS can be dynamic | Repeat ECG during symptoms and use posterior/right leads when indicated | | Routine oxygen in normoxemia | No benefit; potential harm | Give for hypoxemia/respiratory distress | | Nitrates in RV infarction or after PDE5 inhibitor | Severe hypotension | Check hemodynamics and medication history | | Prasugrel in prior stroke/TIA | Major bleeding risk | Use alternative P2Y12 agent | | Ignoring bleeding risk when planning DAPT | Preventable hemorrhage | Use PPI, shortened/modified strategies when appropriate | | Discharge without rehab/lipid plan | Misses high-value prevention | Document secondary prevention before discharge | --- ## Exam-focused review ### Foundation / Step 1 Know plaque rupture/erosion, platelet activation, thrombin/fibrin, subendocardial vulnerability, transmural progression, and the physiologic consequences of reduced coronary blood flow. ### Step 2 CK Priority questions usually ask: **What must happen next?** - STEMI ECG → reperfusion, not stress testing. - Ongoing ischemia with instability → invasive management. - Troponin rise/fall + ischemic evidence without ST elevation → NSTEMI. - Inferior MI + hypotension + clear lungs → consider RV infarction; obtain right-sided leads and avoid nitrates. - New murmur + shock days after MI → mechanical complication. ### Step 3 / Resident Add strategy details: reperfusion timing, fibrinolysis contraindications, antithrombotic selection, bleeding mitigation, shock phenotype, mechanical complications, secondary prevention. ### MRCP / ABIM / boards Expect nuance around: - Type 1 vs type 2 MI - Dynamic hs-cTn interpretation - GRACE risk - Antiplatelet contraindications - DAPT duration in bleeding risk / anticoagulation - Post-MI LV dysfunction therapy - Mechanical complications --- ## Original MCQs #### 1. A 61-year-old man has 90 minutes of crushing chest pain. ECG shows 3 mm ST elevation in V2–V5. Initial hs-cTn is within the reference range. What is the best next step? A. Repeat troponin in 3 hours before treatment B. Exercise stress testing C. Activate immediate reperfusion/primary PCI pathway D. CT coronary angiography first **Answer: C.** Early troponin can be normal. A diagnostic STEMI pattern with an appropriate syndrome requires immediate reperfusion; biomarkers must not delay treatment. #### 2. A patient with inferior STEMI becomes hypotensive after sublingual nitroglycerin. Lungs are clear and JVP is elevated. Best next diagnostic step? A. V4R right-sided ECG lead B. D-dimer C. CT pulmonary angiography D. Stress echocardiography **Answer: A.** The pattern strongly suggests RV infarction with preload dependence. #### 3. Which P2Y12 inhibitor is contraindicated in a patient with prior ischemic stroke? A. Clopidogrel B. Ticagrelor C. Prasugrel D. Cangrelor **Answer: C.** Prasugrel is contraindicated after prior stroke/TIA because of bleeding risk. #### 4. A stable ACS patient undergoes PCI and has no high bleeding risk. What is the contemporary default DAPT duration? A. 48 hours B. 1 month C. 6 weeks D. At least 12 months **Answer: D.** The 2025 ACC/AHA guideline uses at least 12 months as the default in patients without high bleeding risk. #### 5. A patient with NSTEMI has shock, ongoing ischemic pain, and recurrent VT despite initial therapy. What invasive strategy is appropriate? A. Outpatient angiography B. Immediate invasive evaluation C. Stress testing before angiography D. Coronary calcium score **Answer: B.** Very high-risk NSTE-ACS features require immediate invasive care. --- ## References 1. Rao SV, O'Donoghue ML, Ruel M, et al. **2025 ACC/AHA/ACEP/NAEMSP/SCAI Guideline for the Management of Patients With Acute Coronary Syndromes.** *J Am Coll Cardiol.* 2025;85(22):2135–2237. doi: **10.1016/j.jacc.2024.11.009**. https://www.jacc.org/doi/10.1016/j.jacc.2024.11.009 2. American College of Cardiology / American Heart Association. **Top Things to Know: 2025 Guideline for Acute Coronary Syndromes.** Updated February 27, 2025. https://professional.heart.org/en/science-news/2025-guideline-for-the-management-of-patients-with-acute-coronary-syndromes/top-things-to-know 3. Byrne RA, Rossello X, Coughlan JJ, et al. **2023 ESC Guidelines for the management of acute coronary syndromes.** *Eur Heart J.* 2023;44(38):3720–3826. doi: **10.1093/eurheartj/ehad191**. PMID: **37622654**. https://www.escardio.org/guidelines/clinical-practice-guidelines/all-esc-practice-guidelines/acute-coronary-syndromes/ 4. Thygesen K, Alpert JS, Jaffe AS, et al. **Fourth Universal Definition of Myocardial Infarction (2018).** *Circulation.* 2018;138:e618–e651. doi: 10.1161/CIR.0000000000000617. 5. European Society of Cardiology. **Essential Messages from the 2023 ESC Guidelines for the Management of Acute Coronary Syndromes.** 2023. https://www.escardio.org/ 6. Kumbhani DJ, Cibotti-Sun M, Moore MM. **2025 Acute Coronary Syndromes Guideline-at-a-Glance.** *J Am Coll Cardiol.* 2025;85(22):2128–2134. doi: **10.1016/j.jacc.2025.01.018**. 7. Bikdeli B, Ujueta F, Rashedi S, et al. **Antiplatelet and Anticoagulant Therapy in the 2025 ACC/AHA Guideline for Acute Coronary Syndromes: Key Recommendations.** *J Am Coll Cardiol.* 2025. doi: **10.1016/j.jacc.2025.04.002**. --- **Review trigger:** Re-review whenever ACC/AHA or ESC ACS guidance changes, or when major trials alter PCI strategy, cardiogenic-shock support, antiplatelet duration/de-escalation, or lipid-lowering recommendations.1a:T9843,## One-minute summary **Acute ischemic stroke (AIS)** is sudden neurological dysfunction caused by focal cerebral, retinal, or spinal cord ischemia, most often from arterial occlusion. The practical emergency question is not simply “is this a stroke?” but **“is there salvageable brain, and can reperfusion be delivered safely now?”** The 2026 AHA/ASA guideline makes several practice-changing points: [1] - **Tenecteplase 0.25 mg/kg IV (maximum 25 mg)** and **alteplase 0.9 mg/kg IV** are both recommended thrombolytic options for eligible adults presenting within **4.5 hours** of symptom onset or last known well. - A **disabling deficit may warrant thrombolysis even when NIHSS is low**; NIHSS alone should not define disability. - In **mild, non-disabling stroke**, routine thrombolysis has not shown benefit; short-course **dual antiplatelet therapy (DAPT)** is generally preferred when appropriate. - Selected patients with **wake-up stroke or 4.5–9-hour presentation** can receive IV thrombolysis when advanced imaging demonstrates a favorable tissue profile. - Endovascular thrombectomy (EVT) remains standard for eligible **large-vessel occlusion (LVO)** and now extends to selected patients with **larger ischemic cores** and to selected **basilar artery occlusion** up to 24 hours. - Intensive post-reperfusion systolic BP lowering to **<140 mm Hg is not recommended** and may be harmful after successful EVT. - New randomized evidence does **not** support routine thrombectomy for medium/distal-vessel occlusion in populations similar to ESCAPE-MeVO and DISCOUNT. [1,13,14] **Core emergency sequence:** **Recognize stroke → establish last-known-well → glucose → NIHSS → noncontrast head CT → vascular imaging when LVO is possible → IV thrombolysis if eligible without avoidable delay → EVT evaluation in parallel → stroke-unit care and complication prevention.** --- ## 1. Core concepts ### 1.1 Time is brain—but tissue matters too An arterial occlusion creates an **infarct core** surrounded by variably salvageable **ischemic penumbra**. Reperfusion benefit declines with time because collateral circulation eventually fails and the core expands. However, individuals progress at different rates; modern CT perfusion and MRI can identify patients who retain salvageable tissue beyond conventional clock-based windows. [1,5,6] The most important operational principle is therefore: > **Do not delay proven reperfusion therapy while performing tests that will not change immediate eligibility.** For most patients within 4.5 hours with a clinically convincing disabling AIS, a noncontrast CT excluding hemorrhage is sufficient to make an IV thrombolysis decision; CTA/CT perfusion should not unnecessarily postpone treatment. [1] ### 1.2 Treat the patient, not the NIHSS number The **NIH Stroke Scale (NIHSS)** is the standard severity instrument, but it underweights some clinically devastating deficits, especially posterior circulation deficits and isolated functions such as gait, hand dexterity, vision, or language needed for a patient’s occupation. A patient with NIHSS 2 can still have a disabling stroke. [1] Examples of potentially disabling low-NIHSS deficits include: - aphasia that prevents meaningful communication; - dominant-hand weakness preventing functional use; - leg weakness preventing independent ambulation; - hemianopia that meaningfully impairs function; - severe dysarthria affecting communication; - disabling ataxia despite a modest NIHSS score. --- ## 2. Definition and classification ### 2.1 Definition AIS is acute neurological injury from insufficient blood flow caused by arterial occlusion or critical hypoperfusion, resulting in focal brain infarction when ischemia is prolonged. ### 2.2 Etiologic classification A useful conceptual framework is the TOAST-style grouping: | Mechanism | Typical clues | Common examples | |---|---|---| | Large-artery atherosclerosis | Cortical syndrome, carotid/intracranial stenosis, artery-to-artery embolism | Carotid plaque, intracranial atherosclerosis | | Cardioembolism | Abrupt maximal deficit, multiple vascular territories, AF, structural heart disease | Atrial fibrillation, LV thrombus, mechanical valve | | Small-vessel occlusion | Classic lacunar syndrome without cortical signs | Lipohyalinosis from hypertension/diabetes | | Other determined cause | Younger age or distinctive systemic/vascular clue | Dissection, vasculitis, thrombophilia, sickle cell disease | | Undetermined/cryptogenic | No clear mechanism after evaluation or >1 plausible cause | ESUS-type presentations | Etiology matters most after immediate reperfusion decisions because it drives secondary prevention. --- ## 3. Epidemiology and risk factors Ischemic strokes account for the majority of strokes globally and in the United States. The 2026 AHA/ASA guideline notes that ischemic events represent >80% of strokes in the United States and >60% globally. [1] #### Major modifiable risk factors - Hypertension - Atrial fibrillation - Diabetes mellitus - Tobacco exposure - Dyslipidemia - Carotid/intracranial atherosclerosis - Obesity and physical inactivity - Obstructive sleep apnea - Cocaine/amphetamine exposure - Poor adherence to antithrombotic or vascular-risk therapy #### Important nonmodifiable or context-specific risks - Increasing age - Prior stroke/TIA - Family/genetic predisposition - Sickle cell disease - Cancer-associated thrombosis - Pregnancy/postpartum state - Autoimmune/vasculitic disease --- ## 4. Pathophysiology ### 4.1 Ischemic cascade Arterial occlusion lowers cerebral blood flow. ATP depletion leads to membrane depolarization, glutamate release, calcium influx, oxidative stress, mitochondrial dysfunction, cytotoxic edema, and eventually irreversible cellular death. #### Core vs penumbra - **Core:** critically hypoperfused tissue with a high probability of irreversible injury. - **Penumbra:** functionally impaired tissue that remains viable if perfusion is restored promptly. - **Collateral circulation:** the major determinant of how quickly penumbra converts to core. This explains why two patients arriving 6 hours after onset can have very different imaging profiles and treatment opportunities. ### 4.2 Reperfusion injury and hemorrhagic transformation Recanalization can restore function but damaged microvasculature may leak, producing hemorrhagic transformation. Risk rises with larger infarcts, severe hyperglycemia, uncontrolled hypertension, delayed reperfusion, advanced age, and anticoagulant exposure. --- ## 5. Clinical presentation ### 5.1 Common focal syndromes | Vascular territory | Typical findings | |---|---| | Left MCA | Aphasia, right face/arm > leg weakness/sensory loss, gaze preference toward lesion | | Right MCA | Left neglect, left face/arm > leg weakness/sensory loss, visuospatial dysfunction | | ACA | Contralateral leg > arm weakness, abulia, urinary incontinence | | PCA | Contralateral homonymous hemianopia, memory disturbance; thalamic sensory syndromes | | Basilar/posterior circulation | Diplopia, dysarthria, dysphagia, vertigo with focal signs, ataxia, crossed findings, quadriparesis, decreased consciousness | | Lacunar | Pure motor, pure sensory, ataxic hemiparesis, dysarthria-clumsy hand; usually no aphasia/neglect/visual field deficit | #### Posterior circulation warning “Dizziness” alone is common and nonspecific, but **acute vestibular syndrome plus focal neurological signs, severe gait/truncal ataxia, new headache/neck pain, direction-changing nystagmus, skew, or vascular risk** should raise concern for posterior circulation ischemia. --- ## 6. Immediate assessment ### 6.1 First minutes | Task | Why it matters | Immediate action | |---|---|---| | Confirm exact **last known well** | Determines time-based eligibility | Ask patient, family, witnesses, EMS; distinguish symptom discovery from last-known-normal | | ABC stabilization | Hypoxia/hypotension worsen ischemia | Secure airway/ventilation as needed; avoid hypotension | | **Point-of-care glucose** | Hypoglycemia is a stroke mimic and harms brain | Correct significant hypoglycemia immediately | | Focused neurological exam/NIHSS | Quantifies severity and change | Document baseline before reperfusion if feasible | | Noncontrast CT | Excludes hemorrhage and identifies major early ischemia | Obtain urgently | | CTA head/neck when LVO possible | Detects thrombectomy target | Acquire rapidly; do not wait for creatinine when delay threatens EVT eligibility [1] | | Labs | Detect coagulopathy/metabolic confounders | CBC, PT/INR/aPTT as indicated, electrolytes, renal function, troponin; do not delay thrombolysis for routine labs if no reason to suspect abnormality | ### 6.2 Do not miss a stroke mimic | Mimic | Clues favoring mimic | Clues favoring stroke | |---|---|---| | Hypoglycemia | Low glucose, autonomic symptoms, diffuse/confusional state | Persistent focal deficit after glucose correction | | Seizure/Todd paresis | Witnessed convulsion, postictal state | Persistent cortical deficit, vascular occlusion on imaging | | Migraine aura | Positive spreading sensory/visual symptoms, prior similar episodes | Sudden negative deficit maximal at onset | | Functional neurological disorder | Inconsistency, incongruent examination | Objective vascular syndrome/imaging lesion | | Peripheral vestibulopathy | No focal deficit, peripheral HINTS pattern in expert hands | Severe truncal ataxia, focal signs, central ocular motor findings | | Bell palsy | Isolated LMN facial weakness incl. forehead | Forehead-sparing facial weakness with limb deficit/aphasia | | Toxic-metabolic encephalopathy | Global dysfunction | Focal cortical or brainstem syndrome | The hemorrhage risk of IV thrombolysis in stroke mimics is very low, and the 2026 guideline emphasizes avoiding unnecessary delays when the syndrome is otherwise convincing. [1] --- ## 7. Imaging ### 7.1 Noncontrast CT (NCCT) Primary purposes: 1. Exclude intracranial hemorrhage. 2. Detect major established infarction/edema. 3. Estimate early ischemic change using **ASPECTS** in anterior circulation stroke. A normal NCCT does **not** exclude early ischemic stroke. ### 7.2 CTA/MRA Use to identify: - ICA terminus, M1, selected M2, basilar and other occlusions; - tandem cervical/intracranial disease; - dissection; - intracranial atherosclerotic stenosis. The 2026 AHA/ASA guideline states that vascular imaging required for EVT selection should not be delayed for kidney-function testing when such delay could cost reperfusion opportunity. [1] ### 7.3 CT perfusion and MRI Useful for selected: - wake-up stroke; - 4.5–9-hour thrombolysis decisions; - 6–24-hour EVT selection; - uncertain diagnosis when MRI is immediately available without harmful delay. #### Tissue-selection concepts - **DWI–FLAIR mismatch:** diffusion restriction without corresponding FLAIR change suggests relatively recent infarction. - **Perfusion mismatch:** hypoperfused tissue substantially exceeds estimated core, suggesting salvageable penumbra. --- ## 8. Severity and imaging scores ### NIHSS Useful for communication, prognostication, serial change, and treatment pathways. It should not replace individualized assessment of disability. [1] ### ASPECTS Ten-region score for early ischemic change in the MCA territory: - 10 = no visible early ischemic change; - lower scores = larger predicted infarct burden. The modern thrombectomy era has moved beyond a rigid “ASPECTS ≥6 only” rule: randomized large-core trials and the 2026 AHA/ASA guideline support EVT in selected patients with ASPECTS 3–5, and in carefully selected early-window patients even ASPECTS 0–2 may be reasonable. [1,9,10] --- ## 9. Acute management algorithm ```text Suspected acute stroke ↓ ABCs + glucose + exact last-known-well + NIHSS ↓ Urgent NCCT ± CTA head/neck ↓ Hemorrhage? ├─ Yes → hemorrhagic-stroke pathway └─ No ↓ Disabling ischemic deficit? ↓ Within 4.5 h and IVT eligible? ├─ Yes → tenecteplase 0.25 mg/kg (max 25 mg) │ OR alteplase 0.9 mg/kg (max 90 mg) │ WITHOUT delaying parallel EVT evaluation └─ No/unknown onset → advanced imaging when appropriate ↓ Favorable mismatch 4.5–9 h / wake-up? ├─ Yes → consider IV thrombolysis └─ No → no IVT At all times: Is there treatable LVO? ↓ EVT eligibility (early or selected late window; large-core criteria now broader) ↓ Stroke unit + BP/glucose/temp/swallow/DVT prevention + etiologic workup ``` --- ## 10. Intravenous thrombolysis ### 10.1 STANDARD OF CARE — treatment within 4.5 hours For eligible adults with disabling AIS within 4.5 hours, the 2026 AHA/ASA guideline recommends either: [1] #### Tenecteplase - **0.25 mg/kg IV as a single bolus** - **Maximum 25 mg** #### Alteplase - **0.9 mg/kg IV (maximum 90 mg)** - Standard administration: 10% as initial bolus, remainder over 60 minutes. Tenecteplase’s single-bolus administration simplifies transfer and workflow. The 2026 guideline formally places 0.25 mg/kg tenecteplase alongside alteplase as a recommended option. Higher-dose tenecteplase **0.40 mg/kg should not be used for routine AIS thrombolysis**. [1,2] ### 10.2 Disabling vs non-disabling deficit #### Disabling deficit Treat rapidly if otherwise eligible, regardless of a deceptively low NIHSS. [1] #### Mild non-disabling deficit Routine thrombolysis is not recommended because trials have not shown net benefit; DAPT is generally preferred when the stroke is noncardioembolic and the patient meets antiplatelet criteria. [1] ### 10.3 Extended-window thrombolysis For selected patients with: - wake-up stroke; or - symptom onset/last-known-well **4.5–9 hours** earlier, IV thrombolysis may be reasonable if advanced imaging shows a favorable DWI–FLAIR or perfusion mismatch profile. [1,5,6] This is **tissue-selected reperfusion**, not blanket extension of the standard 4.5-hour window. ### 10.4 Blood pressure around thrombolysis #### Before IV thrombolysis A practical trial-based threshold remains: - **SBP <185 mm Hg and DBP <110 mm Hg** before treatment. [1] #### After thrombolysis The 2026 guideline reinforces a more liberal post-IVT target rather than intensive reduction: - generally keep **SBP <180 mm Hg**; - avoid routine intensive targeting **<140 mm Hg**, which does not improve functional outcome. [1] The guideline supportive text recommends maintaining SBP roughly **140–180 mm Hg** after thrombolysis when no other indication dictates a different target. [1] ### 10.5 Major contraindication framework Eligibility is nuanced and should use the current local protocol. High-impact reasons to withhold or defer IV thrombolysis commonly include: - intracranial hemorrhage on imaging; - uncontrolled BP above accepted treatment thresholds despite therapy; - active major bleeding; - recent intracranial surgery/serious head trauma when bleeding risk is prohibitive; - clinically significant coagulopathy or anticoagulant effect at unsafe levels; - strong suspicion of infective endocarditis-related stroke in many protocols; - extensive established infarction when hemorrhage risk outweighs benefit. The 2026 AHA/ASA guideline deliberately modernizes several historical exclusions; avoid using outdated “absolute contraindication” lists without checking current criteria. [1] ### 10.6 After thrombolysis - Frequent neurological and BP checks. - Avoid antiplatelet/anticoagulant treatment during the first 24 hours unless a compelling specialist-directed indication exists. - Obtain follow-up CT/MRI at approximately 24 hours or sooner for neurological deterioration before starting routine antithrombotic therapy. - Watch for orolingual angioedema and symptomatic intracranial hemorrhage. #### Suspected post-thrombolysis intracranial hemorrhage Stop thrombolytic infusion if still running; obtain emergent CT, CBC, fibrinogen, coagulation studies, and activate stroke/neurocritical-care/hematology protocols for reversal and hemostatic management. Exact reversal regimen is institution-specific. --- ## 11. Endovascular thrombectomy (EVT) ### 11.1 STANDARD OF CARE — proximal anterior circulation LVO EVT is one of the most effective acute neurological interventions. The 2026 guideline recommends thrombectomy for eligible patients with proximal ICA/M1 occlusion in the early window and expands eligibility for patients with larger predicted cores. [1] #### Early window (0–6 hours) A strong evidence base supports EVT for appropriate ICA/M1 LVO with clinically meaningful deficit. The 2026 guideline explicitly includes selected patients with **ASPECTS 3–10** and NIHSS ≥6 under standard criteria; selected ASPECTS 0–2 patients may also reasonably be considered when other features favor benefit. [1] #### Late window (6–24 hours) Selected patients with proximal anterior-circulation LVO can benefit up to 24 hours based on clinical and imaging selection. Large-core trials such as SELECT2 and ANGEL-ASPECT expanded the treatable population beyond the small-core DAWN/DEFUSE-3 paradigm. [1,7-10] ### 11.2 Basilar artery occlusion The 2026 AHA/ASA guideline gives a strong recommendation for EVT in selected patients with **basilar artery occlusion within 24 hours**, particularly those with: - prestroke mRS 0–1; - **NIHSS ≥10**; - **PC-ASPECTS ≥6**. [1] ATTENTION and BAOCHE were major trials establishing benefit in this previously uncertain population. [11,12] ### 11.3 Do not delay IV thrombolysis for EVT When a patient is eligible for IV thrombolysis and also has an LVO, treatment is generally **bridging therapy**: give IV thrombolysis promptly and proceed to thrombectomy rather than waiting to see whether IV treatment works. [1] ### 11.4 Blood pressure after EVT The 2026 guideline incorporates new randomized data showing that aggressive BP lowering can be harmful after successful recanalization: - routine targeting of **SBP <140 mm Hg after successful EVT is harmful/not recommended** when there is no separate indication for such a low target. [1] Avoid hypotension and maintain adequate cerebral perfusion. ### 11.5 Medium/distal vessel occlusion — not routine standard care **EMERGING/NEGATIVE EVIDENCE:** ESCAPE-MeVO (2025) found no improvement in 90-day outcome with EVT for medium-vessel occlusion and observed higher mortality and more symptomatic intracranial hemorrhage in the intervention group. [13] DISCOUNT, published in 2026, similarly did not show improved good functional outcome and reported more symptomatic hemorrhage with thrombectomy. [14] **Practical implication:** Do not extrapolate the dramatic benefit of ICA/M1 thrombectomy to all M2/M3/ACA/PCA distal occlusions. Individual selected cases may still be discussed with neurointerventional experts, but routine thrombectomy for populations matching these trials is not evidence-based. --- ## 12. General supportive care ### Oxygenation - Maintain adequate oxygenation. - Supplemental oxygen is not routinely required in a nonhypoxemic patient. - Treat airway compromise, aspiration, pneumonia, or respiratory failure promptly. ### Blood pressure if no reperfusion therapy When no IVT/EVT is planned and there is no separate hypertensive emergency, routine early BP lowering does not improve outcome when BP is below approximately **220/120 mm Hg**. In severe hypertension, cautious individualized reduction—often around 15% initially—is used. [1] Urgent BP treatment may still be necessary for aortic dissection, acute coronary syndrome, pulmonary edema, hypertensive encephalopathy, preeclampsia/eclampsia, or another compelling condition. ### Glucose - Correct significant hypoglycemia. - Treat marked hyperglycemia, commonly when persistent glucose is >180 mg/dL, while avoiding hypoglycemia. - **Do not target 80–130 mg/dL intensively**; the SHINE trial and 2026 guideline show no functional benefit and more severe hypoglycemia. [1] ### Temperature - Treat fever and investigate infection. - The 2026 guideline supports protocols maintaining normothermia and treating temperatures >37.5°C. [1] - Therapeutic hypothermia is not routine AIS care. ### Swallowing - Screen for dysphagia before oral food, liquids, and medications when feasible. - Provide oral hygiene and aspiration precautions. - Use enteral support when oral intake is unsafe. ### DVT prevention - Early mobilization when safe. - Intermittent pneumatic compression for immobile patients is evidence-based. - Pharmacologic prophylaxis is individualized to hemorrhagic risk and reperfusion status. --- ## 13. Antiplatelet and anticoagulant therapy ### 13.1 Aspirin and DAPT For noncardioembolic AIS not treated with thrombolysis, antiplatelet therapy is initiated early after hemorrhage is excluded. #### Short-course DAPT The 2026 guideline supports **aspirin + clopidogrel for 21 days** in selected patients with: - minor noncardioembolic AIS (generally NIHSS ≤5 depending on the specific pathway); or - high-risk TIA; - no IV thrombolysis; - low enough bleeding risk. [1] This approach derives from CHANCE/POINT-era evidence and should not be extended indefinitely because bleeding risk rises with prolonged dual therapy. ### 13.2 Atrial fibrillation Cardioembolic stroke usually requires long-term oral anticoagulation, but timing depends on infarct size, hemorrhagic transformation, reperfusion treatment, and bleeding risk. The 2026 AIS guideline states that in carefully selected patients—especially milder strokes—**earlier oral anticoagulation is reasonable and appears low risk** compared with delayed initiation, while acknowledging uncertainty about the efficacy of preventing very early recurrence. [1] This is consistent with modern randomized evidence such as ELAN, which supports individualized early DOAC initiation in many patients rather than rigid long delays. [15] --- ## 14. Etiologic workup after stabilization A complete stroke mechanism evaluation commonly includes: - continuous telemetry/ECG for atrial fibrillation; - vascular imaging of neck and intracranial circulation; - transthoracic echocardiography when cardioembolism is possible; - prolonged rhythm monitoring for cryptogenic embolic stroke; - HbA1c and lipid profile; - selective TEE, thrombophilia, vasculitis, infectious, or genetic testing when indicated; - cervical artery dissection evaluation in compatible presentations. Avoid broad low-yield thrombophilia testing in older patients with a conventional atherosclerotic/cardioembolic explanation unless history suggests otherwise. --- ## 15. Important complications | Complication | Warning signs | Key response | |---|---|---| | Hemorrhagic transformation | New headache, vomiting, hypertension, worsening deficit, reduced consciousness | Emergent CT; stop antithrombotics; reverse relevant agents; neurocritical-care input | | Malignant cerebral edema | Declining consciousness, worsening hemiparesis, gaze changes, pupillary abnormalities | Neurocritical care; osmotherapy as bridge; urgent neurosurgical evaluation | | Aspiration pneumonia | Fever, cough, hypoxemia after dysphagia | Swallow precautions, antibiotics when infection established | | Seizure | Convulsion or unexplained episodic decline | Treat clinical seizures; routine prophylaxis is not standard | | DVT/PE | Leg swelling, unexplained hypoxia/tachycardia | Prophylaxis; diagnostic workup if suspected | | Recurrent stroke | New focal deficit | Repeat acute stroke pathway; reassess eligibility for reperfusion | | Depression/delirium | Mood/cognitive change | Screening, rehabilitation, medication review, supportive care | ### Malignant MCA infarction Large hemispheric infarction can cause life-threatening edema over several days. **Early decompressive hemicraniectomy** reduces mortality and severe disability in appropriately selected patients; benefit is strongest in younger patients but can extend to selected older adults with individualized goals-of-care discussion. --- ## 16. Secondary prevention ### 16.1 Blood pressure Long-term hypertension control is one of the most effective recurrent-stroke prevention interventions. Avoid translating permissive acute-stroke BP management into chronic care. ### 16.2 Lipids High-intensity statin therapy is standard after atherosclerotic ischemic stroke unless contraindicated. For very-high-risk atherosclerotic disease, add-on ezetimibe or PCSK9-directed therapy may be needed to achieve guideline LDL targets. ### 16.3 Carotid disease Symptomatic ipsilateral carotid stenosis can require carotid endarterectomy, with benefit depending on stenosis severity, age/sex, procedural risk, and timing. Early specialist evaluation is essential. ### 16.4 Lifestyle - Smoking cessation - Exercise and rehabilitation - Mediterranean-style dietary pattern - Diabetes management - Weight management - Sleep apnea evaluation where indicated --- ## 17. Special populations ### Pregnancy Stroke in pregnancy requires coordinated neurology, maternal-fetal medicine, anesthesia, and neurointerventional care. Pregnancy is not automatically an exclusion from reperfusion; risks and benefits depend on maternal threat, gestational age, bleeding risk, and treatment modality. ### Children The 2026 AHA/ASA guideline includes pediatric interventional recommendations for the first time. Pediatric AIS requires expert center involvement because causes, vessel caliber, dosing, and evidence differ from adults. [1] ### Sickle cell disease Acute focal deficit in sickle cell disease requires urgent stroke-center and hematology management; transfusion/exchange transfusion is central to disease-specific care. ### Cervical artery dissection Dissection is an important cause in younger adults. The 2026 guideline concludes that either antiplatelet therapy or anticoagulation can be reasonable after AIS due to dissection, reflecting limited comparative evidence. [1] --- ## 18. Acute management checklist ### First 10 minutes - [ ] Activate stroke pathway. - [ ] Establish last-known-well. - [ ] ABCs; avoid hypotension/hypoxemia. - [ ] Point-of-care glucose. - [ ] NIHSS/focused deficit assessment. - [ ] Noncontrast head CT. - [ ] CTA head/neck if LVO suspected. - [ ] Determine whether deficit is **disabling**, not merely whether NIHSS is “low.” ### Reperfusion decision - [ ] Within 4.5 hours and eligible? Give **tenecteplase 0.25 mg/kg (max 25 mg)** or **alteplase 0.9 mg/kg (max 90 mg)**. - [ ] BP <185/110 before IVT. - [ ] Do not delay IVT for unnecessary advanced imaging. - [ ] Evaluate EVT in parallel when LVO is possible. - [ ] For wake-up/4.5–9-hour stroke, use advanced imaging selection. - [ ] For 6–24-hour LVO, evaluate late-window EVT eligibility. ### First 24 hours - [ ] Stroke-unit monitoring. - [ ] Maintain appropriate BP; avoid intensive SBP <140 after reperfusion unless another indication exists. - [ ] Treat fever and significant glucose derangement. - [ ] Swallow screen before oral intake. - [ ] DVT prevention. - [ ] Repeat imaging if deterioration; routine post-IVT imaging before antithrombotics. - [ ] Begin etiologic evaluation. --- ## 19. Common pitfalls | Pitfall | Why it is dangerous | Better approach | |---|---|---| | “NIHSS is only 2, so no thrombolysis” | Low NIHSS can still be disabling | Judge functional disability | | Waiting for MRI in a clear <4.5 h disabling stroke | Loses reperfusion benefit | NCCT is usually enough for IVT decision | | Waiting for creatinine before CTA in suspected LVO | Delays EVT | Proceed rapidly when vascular imaging is required [1] | | Treating BP aggressively to “normal” | Can reduce penumbral perfusion | Use reperfusion-specific targets | | Targeting SBP <140 after successful EVT | RCT evidence suggests harm | Avoid overly intensive reduction [1] | | Assuming wake-up stroke is untreatable | Tissue imaging may identify benefit | DWI-FLAIR/perfusion selection | | Giving routine EVT for distal/medium occlusions | RCTs have not shown benefit and may show harm | Individualize; not routine standard care [13,14] | | Starting oral intake without dysphagia assessment | Aspiration risk | Screen swallowing first | --- ## 20. Exam-focused review ### Foundation / Step 1 Know the ischemic cascade, collateral circulation, infarct core vs penumbra, and why reperfusion must be early. ### Step 2 CK Prioritize **stabilization and reperfusion before definitive etiologic workup**. A patient with sudden aphasia and right weakness who arrives 90 minutes after last-known-well needs glucose and emergent CT—not carotid ultrasound, echocardiography, or MRI first. ### Step 3 / resident Know: - tenecteplase 0.25 mg/kg max 25 mg; - alteplase 0.9 mg/kg max 90 mg; - pre-IVT BP <185/110; - do not intensively lower post-reperfusion SBP <140 without a separate indication; - IVT and EVT are complementary when both are indicated; - selected late-window and large-core patients can benefit from EVT. ### MRCP/ABIM/board level Distinguish: - low NIHSS vs non-disabling deficit; - proximal LVO vs medium/distal occlusion; - clock-based vs tissue-based treatment windows; - cardioembolic vs noncardioembolic secondary prevention; - acute permissive hypertension vs long-term hypertension control. --- ## 21. Original MCQs #### Question 1 A 67-year-old right-handed teacher develops isolated expressive aphasia 90 minutes ago. NIHSS is 2. CT shows no hemorrhage. BP is 168/94 mm Hg. Which principle best guides treatment? A. NIHSS <4 excludes thrombolysis B. Aphasia may be disabling despite a low NIHSS C. MRI is mandatory before thrombolysis D. Wait 24 hours to see whether symptoms resolve **Answer: B.** The 2026 guideline emphasizes disability rather than an NIHSS cutoff alone. Disabling deficits should be treated rapidly if otherwise eligible. [1] #### Question 2 Which IV thrombolytic regimen is recommended by the 2026 AHA/ASA guideline? A. Tenecteplase 0.40 mg/kg B. Tenecteplase 0.25 mg/kg, maximum 25 mg C. Alteplase 1.5 mg/kg D. Streptokinase infusion **Answer: B.** Tenecteplase 0.25 mg/kg (max 25 mg) or alteplase 0.9 mg/kg are recommended options. [1] #### Question 3 A patient with an LVO is eligible for both IV thrombolysis and thrombectomy. What is the best strategy? A. Skip IV therapy and wait for EVT in all cases B. Give IV thrombolysis promptly and proceed with EVT evaluation without delay C. Wait 60 minutes after thrombolysis to assess response before transfer D. Anticoagulate with heparin first **Answer: B.** Eligible IV thrombolysis should not be delayed or withheld simply because EVT is planned. [1] #### Question 4 After successful EVT, which routine BP strategy is specifically discouraged by current evidence? A. Avoiding hypotension B. Treating severe hypertension C. Intensive SBP targeting <140 mm Hg without another indication D. Frequent BP measurement **Answer: C.** Intensive SBP lowering below 140 mm Hg after successful EVT may worsen functional outcomes. [1] #### Question 5 A patient wakes with hemiparesis; last known well was 7 hours ago. CT excludes hemorrhage. Which statement is correct? A. IV thrombolysis is always contraindicated after 4.5 hours B. Advanced imaging can identify selected patients for extended-window thrombolysis C. Only aspirin is possible D. MRI mismatch has no role **Answer: B.** Selected wake-up or 4.5–9-hour strokes may receive thrombolysis based on DWI-FLAIR or perfusion mismatch. [1,5,6] #### Question 6 Which statement about medium/distal vessel occlusion is most accurate as of September 2026? A. EVT is proven routine standard care for all M3 occlusions B. Recent randomized trials failed to demonstrate routine benefit and reported safety concerns C. EVT is contraindicated in every distal occlusion D. All patients should receive systemic heparin **Answer: B.** ESCAPE-MeVO and DISCOUNT did not show routine functional benefit; thrombectomy should not be reflexively extrapolated from proximal LVO evidence. [13,14] #### Question 7 A patient with AIS is not receiving reperfusion therapy, has BP 196/108 mm Hg, and no other hypertensive emergency. Which approach is most appropriate? A. Immediately normalize to 120/80 B. Routine aggressive reduction is not required simply because BP is elevated C. Nitroprusside until SBP <100 D. Mandatory IV labetalol to SBP <140 **Answer: B.** In nonreperfused AIS, routine early lowering below the severe-hypertension threshold does not improve outcome; avoid compromising cerebral perfusion. [1] #### Question 8 Which in-hospital glucose strategy is supported by the 2026 guideline? A. Target 80–130 mg/dL with intensive insulin in all patients B. Ignore glucose after the initial value C. Correct hypoglycemia and marked hyperglycemia, but avoid intensive 80–130 mg/dL targeting D. Maintain glucose >250 mg/dL **Answer: C.** Intensive glucose control to 80–130 mg/dL did not improve outcomes and increased severe hypoglycemia. [1] --- ## 22. Current guideline changes and recent research ### STANDARD OF CARE — 2026 changes 1. **Tenecteplase 0.25 mg/kg is now a fully endorsed alternative to alteplase** within the 4.5-hour window. [1] 2. **Thrombolysis is guided by disability, not an NIHSS threshold alone.** [1] 3. **Extended-window thrombolysis** is supported for selected imaging-defined patients. [1] 4. **Large-core EVT eligibility is broader** based on SELECT2, ANGEL-ASPECT, LASTE and related trials. [1,9,10] 5. **Basilar EVT up to 24 hours** is standard in selected NIHSS ≥10, favorable-PC-ASPECTS patients. [1,11,12] 6. **Intensive SBP <140 after EVT is harmful/not recommended.** [1] 7. Intensive glucose control to **80–130 mg/dL is not recommended**. [1] ### EMERGING/NEGATIVE EVIDENCE #### Medium/distal vessel thrombectomy ESCAPE-MeVO (NEJM 2025) found no 90-day functional benefit from EVT for medium-vessel occlusion; symptomatic ICH and mortality were higher in the EVT arm. [13] DISCOUNT (JAMA 2026) similarly found no improvement in good outcome, with symptomatic hemorrhage 11% vs 3% in thrombectomy vs medical treatment. [14] **Interpretation:** Routine EVT for medium/distal occlusion remains unsupported; future work may identify narrower subgroups. ### EXPERIMENTAL/INVESTIGATIONAL - Neuroprotective drugs as an adjunct to reperfusion - Direct-to-angiosuite pathways outside validated systems - Thrombectomy beyond 24 hours - New devices/selection approaches for distal occlusion - Selective brain cooling These should not replace proven rapid reperfusion pathways. --- ## 23. References 1. Prabhakaran S, Gonzalez NR, Zachrison KS, et al. **2026 Guideline for the Early Management of Patients With Acute Ischemic Stroke: A Guideline From the American Heart Association/American Stroke Association.** *Stroke*. Published January 26, 2026. doi: **10.1161/STR.0000000000000513**. https://www.ahajournals.org/doi/10.1161/STR.0000000000000513 2. Alamowitch S, Turc G, Palaiodimou L, et al. **European Stroke Organisation expedited recommendation on tenecteplase for acute ischaemic stroke.** *Eur Stroke J*. 2023;8(1). doi: **10.1177/23969873221150022**. https://journals.sagepub.com/doi/10.1177/23969873221150022 3. NINDS rt-PA Stroke Study Group. **Tissue plasminogen activator for acute ischemic stroke.** *N Engl J Med*. 1995;333:1581-1587. doi: **10.1056/NEJM199512143332401**. 4. Hacke W, Kaste M, Bluhmki E, et al. **Thrombolysis with alteplase 3 to 4.5 hours after acute ischemic stroke.** *N Engl J Med*. 2008;359:1317-1329. doi: **10.1056/NEJMoa0804656**. 5. Thomalla G, Simonsen CZ, Boutitie F, et al. **MRI-Guided Thrombolysis for Stroke with Unknown Time of Onset (WAKE-UP).** *N Engl J Med*. 2018;379:611-622. doi: **10.1056/NEJMoa1804355**. 6. Ma H, Campbell BCV, Parsons MW, et al. **Thrombolysis Guided by Perfusion Imaging up to 9 Hours after Onset of Stroke (EXTEND).** *N Engl J Med*. 2019;380:1795-1803. doi: **10.1056/NEJMoa1813046**. 7. Nogueira RG, Jadhav AP, Haussen DC, et al. **Thrombectomy 6 to 24 Hours after Stroke with a Mismatch between Deficit and Infarct (DAWN).** *N Engl J Med*. 2018;378:11-21. doi: **10.1056/NEJMoa1706442**. 8. Albers GW, Marks MP, Kemp S, et al. **Thrombectomy for Stroke at 6 to 16 Hours with Selection by Perfusion Imaging (DEFUSE 3).** *N Engl J Med*. 2018;378:708-718. doi: **10.1056/NEJMoa1713973**. 9. Sarraj A, Hassan AE, Abraham MG, et al. **Trial of Endovascular Thrombectomy for Large Ischemic Strokes (SELECT2).** *N Engl J Med*. 2023;388:1259-1271. doi: **10.1056/NEJMoa2214403**. https://www.nejm.org/doi/10.1056/NEJMoa2214403 10. Huo X, Ma G, Tong X, et al. **Trial of Endovascular Therapy for Acute Ischemic Stroke with Large Infarct (ANGEL-ASPECT).** *N Engl J Med*. 2023;388:1272-1283. doi: **10.1056/NEJMoa2213379**. 11. Tao C, Nogueira RG, Zhu Y, et al. **Trial of Endovascular Treatment of Acute Basilar-Artery Occlusion (ATTENTION).** *N Engl J Med*. 2022;387:1361-1372. doi: **10.1056/NEJMoa2206317**. 12. Jovin TG, Li C, Wu L, et al. **Trial of Thrombectomy 6 to 24 Hours after Stroke Due to Basilar-Artery Occlusion (BAOCHE).** *N Engl J Med*. 2022;387:1373-1384. doi: **10.1056/NEJMoa2207576**. 13. Goyal M, Ospel JM, Ganesh A, et al; ESCAPE-MeVO Investigators. **Endovascular Treatment of Stroke Due to Medium-Vessel Occlusion.** *N Engl J Med*. 2025;392:1385-1395. doi: **10.1056/NEJMoa2411668**. https://www.nejm.org/doi/10.1056/NEJMoa2411668 14. Clarençon F, Bala F, Baptiste A, et al. **Mechanical Thrombectomy in Ischemic Stroke With a Medium or Distal Arterial Occlusion: The DISCOUNT Randomized Clinical Trial.** *JAMA*. 2026;336(9):755-764. doi: **10.1001/jama.2026.8977**. PMID: **42485024**. 15. Fischer U, Koga M, Strbian D, et al. **Early versus Later Anticoagulation for Stroke with Atrial Fibrillation (ELAN).** *N Engl J Med*. 2023;388:2411-2421. doi: **10.1056/NEJMoa2303048**. 16. Kleindorfer DO, Towfighi A, Chaturvedi S, et al. **2021 Guideline for the Prevention of Stroke in Patients With Stroke and Transient Ischemic Attack.** *Stroke*. 2021;52:e364-e467. doi: **10.1161/STR.0000000000000375**. --- ### Bottom line Acute ischemic stroke is a **reperfusion emergency**. The highest-yield decisions are to establish last-known-well, identify whether the deficit is disabling, exclude hemorrhage, detect LVO, and deliver IV thrombolysis and/or thrombectomy without avoidable delay. In 2026, the treatable population is broader than it was a decade ago—but treatment remains highly selection-dependent: **large-core and basilar occlusion thrombectomy have moved into standard care for selected patients, while routine medium/distal-vessel thrombectomy has not.**1b:Tc5b9,## One-minute summary **Acute pulmonary embolism (PE)** is obstruction of the pulmonary arterial circulation by thrombus, usually arising from deep veins of the legs or pelvis. The immediate threat is **acute right-ventricular (RV) pressure overload**, which may progress from compensated RV strain to reduced left-ventricular preload, systemic hypotension, obstructive shock, and cardiac arrest. The 2026 multisociety AHA/ACC guideline introduces a new **A–E Acute PE Clinical Category system** that moves beyond the older low/intermediate/high-risk labels. [1,3] - **A:** incidental/asymptomatic PE. - **B:** symptomatic PE with a low clinical severity score. - **C:** symptomatic PE with an elevated clinical severity score, stratified by RV dysfunction and cardiac biomarkers. - **D:** incipient cardiopulmonary failure, such as transient hypotension or normotensive shock/end-organ hypoperfusion. - **E:** established cardiopulmonary failure, including persistent hypotension with shock or cardiac arrest. [1,3] The core clinical pathway is: **Estimate pretest probability → use PERC only in truly very-low-risk patients → use D-dimer when appropriate → CTPA (or V/Q when needed) → confirm PE → immediately risk-stratify → anticoagulate unless contraindicated → identify who is safe for outpatient care vs who needs monitored hospitalization or advanced reperfusion.** High-yield 2026 practice points: [1] - A negative **age-adjusted D-dimer** can avoid imaging in appropriate low/intermediate-probability patients over age 50. - **CTPA** is the usual first-line definitive test; V/Q scanning is valuable when iodinated contrast is unsuitable. - **LMWH is preferred over UFH** when initial parenteral anticoagulation is required in most C1–E1 patients. - **DOACs are preferred over vitamin K antagonists** for most eligible adults. - Advanced reperfusion therapies are **reasonable in Category E1** and may be considered in **D1–D2**; routine systemic thrombolysis is harmful in A–C2. - **PERT assessment is recommended** for higher-risk categories to improve care delivery. - Follow-up should include anticoagulation review and screening for persistent dyspnea/functional limitation and chronic thromboembolic pulmonary disease (CTEPD). Two major randomized trials published after the guideline evidence cutoff—**HI-PEITHO** and **PRAGUE-26**—showed fewer early clinical deterioration events with catheter-directed thrombolysis in selected intermediate-risk/intermediate-high-risk patients. These are important **emerging evidence**, but they do not yet justify indiscriminate catheter treatment of all normotensive PE. [15,16] --- ## 1. Definition and core concepts ### 1.1 Definition Acute PE is partial or complete obstruction of one or more pulmonary arteries by embolic material, overwhelmingly thrombus. Most thrombi originate from lower-extremity or pelvic deep venous thrombosis (DVT), although upper-extremity catheter-associated thrombosis and other sources occur. #### Anatomical terms - **Subsegmental PE:** clot limited to subsegmental pulmonary arteries. - **Segmental PE:** segmental branch involvement. - **Lobar/proximal PE:** lobar or main pulmonary artery involvement. - **Saddle PE:** thrombus straddling the pulmonary artery bifurcation. This is an anatomical description, **not a severity category**; a saddle embolus can be hemodynamically stable, while a smaller clot burden can be fatal in a patient with limited cardiopulmonary reserve. ### 1.2 The main physiological problem is RV afterload Abrupt obstruction plus vasoconstriction increases pulmonary vascular resistance. The RV, a thin-walled chamber adapted to a low-pressure system, dilates under acute pressure load. RV wall tension and oxygen demand rise while coronary perfusion can fall. The interventricular septum shifts toward the LV, impairing LV filling. Cardiac output declines; systemic hypotension further reduces RV coronary perfusion, creating a vicious cycle. #### Hemodynamic spiral ```text Pulmonary arterial obstruction ↓ ↑ Pulmonary vascular resistance ↓ RV dilation + ↑ wall stress ↓ Tricuspid regurgitation + septal shift ↓ ↓ LV preload and cardiac output ↓ Hypotension / systemic hypoperfusion ↓ ↓ RV coronary perfusion ↓ RV ischemia → worsening RV failure ↓ Obstructive shock / cardiac arrest ``` This explains why **blood pressure alone is insufficient** for risk assessment: a patient may be normotensive while already developing low cardiac output, lactate elevation, acute kidney injury, oliguria, or altered mental status. --- ## 2. Epidemiology and risk factors PE is a major manifestation of venous thromboembolism (VTE). Risk follows **Virchow’s triad**: venous stasis, endothelial injury, and hypercoagulability. ### 2.1 Major provoking factors #### Strong transient factors - Major surgery, especially orthopedic/pelvic surgery - Major trauma or fracture - Prolonged hospitalization or severe acute illness - Marked immobilization - Pregnancy and postpartum state #### Persistent factors - Active cancer - Chronic inflammatory or autoimmune disease - Persistent immobility - Antiphospholipid syndrome (APS) - Selected inherited thrombophilias #### Common acquired risk factors - Prior VTE - Increasing age - Obesity - Estrogen-containing hormonal therapy - Heart failure - Chronic lung disease - Nephrotic syndrome - Central venous catheters - Myeloproliferative neoplasms ### 2.2 Provoked vs unprovoked is clinically useful—but imperfect The traditional binary distinction helps estimate recurrence risk, but risk is a continuum. A PE after major surgery is very different from a PE after a minor transient trigger in a patient with obesity, inflammatory disease, and previous VTE. Modern duration decisions increasingly incorporate **persistent risk, recurrence risk, bleeding risk, and patient preference**, rather than relying on a single label. [1,17] --- ## 3. Clinical presentation PE ranges from asymptomatic incidental imaging findings to sudden cardiac arrest. ### 3.1 Common symptoms - Acute or progressive dyspnea - Pleuritic chest pain - Nonpleuritic chest pressure - Cough - Hemoptysis - Syncope or presyncope - Palpitations - Unilateral leg pain/swelling ### 3.2 Common signs - Tachycardia - Tachypnea - Hypoxemia - Fever (usually low grade if present) - Unilateral leg swelling/tenderness - Elevated JVP - RV heave - Loud P2 - New tricuspid regurgitation murmur - Hypotension, cool extremities, altered mental status, oliguria in advanced disease ### 3.3 Red flags for impending deterioration - Syncope with persistent tachycardia or borderline BP - SBP near 90–110 mm Hg or a meaningful fall from baseline - Rising lactate - Increasing oxygen requirement - RR ≥30/min - New confusion - Oliguria/acute kidney injury - Marked RV dilation or reduced RV function - Elevated troponin with RV dysfunction - Free-floating right-heart clot-in-transit A normotensive patient with several of these features may be in **incipient cardiopulmonary failure**, not “stable PE.” [1] --- ## 4. Differential diagnosis | Condition | Features that overlap | Clues favoring alternative diagnosis | |---|---|---| | Acute coronary syndrome | Chest pain, dyspnea, troponin elevation | Ischemic ECG pattern/coronary syndrome; remember PE can also elevate troponin | | Pneumonia | Dyspnea, pleuritic pain, fever, hypoxemia | Focal infiltrate, infectious prodrome; PE and pneumonia can coexist | | Pneumothorax | Sudden dyspnea/pleuritic pain | Unilateral absent breath sounds, pleural line on ultrasound, CXR findings | | Acute aortic syndrome | Chest/back pain, syncope | Pulse/BP differential, aortic imaging findings | | Acute heart failure | Dyspnea, hypoxemia, elevated BNP | Pulmonary edema, LV dysfunction; PE can precipitate RV-predominant failure | | Pericarditis | Pleuritic pain | Positional pain, diffuse ST elevation/PR depression | | COPD/asthma exacerbation | Dyspnea, tachycardia | Wheeze/known disease; PE remains possible if unexplained deterioration | | Panic/hyperventilation | Dyspnea, chest discomfort | Diagnosis of exclusion when PE probability is nontrivial | | Sepsis | Tachycardia, hypotension, lactate elevation | Infection source; PE can coexist with systemic illness | --- ## 5. Diagnostic strategy: probability before testing The biggest diagnostic error is ordering tests without first considering **pretest probability**. D-dimer is useful when disease probability is low enough that a negative result safely rules out PE; it is inefficient in high-probability patients and frequently positive in hospitalized, elderly, pregnant, inflammatory, postoperative, and cancer populations. ### 5.1 Step 1 — Is the patient unstable? If the patient has shock or cardiac arrest and PE is strongly suspected: - Resuscitate immediately. - Obtain bedside echocardiography/POCUS if it can be performed without delaying treatment. - Obtain CTPA if the patient can safely reach CT. - Activate PERT/critical care/interventional/surgical resources early. Echocardiography is **not recommended to confirm or exclude PE in a stable suspected case**, because RV findings are not sufficiently specific; its major value is risk stratification and bedside assessment in unstable patients. [1] ### 5.2 Step 2 — Estimate clinical probability Validated tools include: - Wells score - Revised Geneva score - Clinical gestalt in experienced hands The practical purpose is to classify the patient into a pathway where PE is: - very unlikely, - low/intermediate probability, or - high probability. ### 5.3 PERC — only for very-low-risk patients The **Pulmonary Embolism Rule-out Criteria (PERC)** may allow no further testing when clinician-estimated pretest probability is very low (commonly <15%) and **all 8 criteria are absent**: 1. Age ≥50 years 2. Pulse ≥100/min 3. SpO₂ <95% 4. Unilateral leg swelling 5. Hemoptysis 6. Estrogen use 7. Prior DVT/PE 8. Recent surgery or trauma requiring hospitalization If any PERC criterion is positive, PERC does not rule out PE—move to a D-dimer or imaging strategy depending on pretest probability. [1] **Pitfall:** PERC is not a “PE score” to apply indiscriminately to every patient with chest pain. ### 5.4 D-dimer #### Standard threshold A highly sensitive D-dimer below the assay cutoff (often 500 µg/L FEU) excludes PE in appropriately selected low/intermediate-probability patients. #### Age-adjusted D-dimer For patients older than 50 years, a commonly validated threshold is: **Age × 10 µg/L FEU** Example: age 72 → negative threshold <720 µg/L FEU, assuming the assay uses compatible FEU units. [1,5] Always confirm laboratory units and assay convention; D-dimer units are not interchangeable. ### 5.5 YEARS strategy The YEARS algorithm assesses three items: - Clinical signs of DVT - Hemoptysis - PE judged the most likely diagnosis Typical thresholds: [6] - **No YEARS items:** D-dimer <1000 µg/L FEU can exclude PE. - **≥1 YEARS item:** D-dimer <500 µg/L FEU can exclude PE. A pregnancy-adapted YEARS pathway is an evidence-based option in selected pregnant patients and can reduce unnecessary chest imaging when applied correctly. [1] --- ## 6. Imaging and bedside tests ### 6.1 CTPA **CT pulmonary angiography (CTPA)** is the standard definitive imaging test in most adults. It provides: - direct visualization of emboli; - clot location/burden; - alternative diagnoses; - RV/LV ratio for risk stratification; - signs of chronic thromboembolic disease. The 2026 guideline recommends **numerical RV/LV ratio reporting** rather than subjective RV enlargement when CTPA is performed. [1] ### 6.2 Ventilation-perfusion (V/Q) scanning V/Q scanning is especially useful when: - iodinated contrast is contraindicated; - severe contrast allergy exists; - renal function makes CTPA undesirable in the individual context; - radiation distribution is a concern, including selected pregnancy pathways; - chest radiograph is relatively normal, improving interpretability. ### 6.3 Compression ultrasonography Finding a proximal DVT can establish VTE and may support treatment when chest imaging is impossible or undesirable, but a negative leg ultrasound does **not** exclude PE. ### 6.4 Echocardiography In confirmed PE, echo assists risk assessment by evaluating RV size/function and pulmonary pressures. The August 11, 2026 correction to the AHA/ACC guideline clarified right-heart echocardiographic parameters. [2] | Parameter | Abnormal / concerning threshold or finding | |---|---| | RV/LV end-diastolic ratio | >0.9 abnormal in the guideline framework | | RV end-diastolic dimension | ≥30 mm in an RV-focused parasternal long-axis view, or basal RV EDD ≥41 mm in an apical RV-focused view | | TAPSE | ≤1.7 cm abnormal | | TDI S′ velocity | ≤9.5 cm/s abnormal | | TR velocity | ≥2.9 m/s suggests pulmonary hypertension | | Other findings | McConnell sign, paradoxical septal motion, reduced IVC respirophasic collapse, elevated estimated RV systolic pressure | No single echo sign proves PE; interpret the overall pattern and clinical context. ### 6.5 ECG Possible findings: - Sinus tachycardia (most common) - Right bundle-branch block - Right-axis deviation - Anterior T-wave inversion - S1Q3T3 pattern - Atrial arrhythmias **S1Q3T3 is neither sensitive nor specific** and should never be used to rule in or rule out PE. ### 6.6 Laboratory biomarkers #### Troponin Elevation reflects RV myocardial injury and is prognostic in confirmed PE; it is not specific for PE. #### BNP/NT-proBNP Reflects RV wall stress and helps risk stratification. #### Lactate Elevated lactate can reveal low-output physiology/end-organ hypoperfusion despite preserved blood pressure. In the 2026 framework it is important for identifying **normotensive shock / Category D2 physiology**. [1,3] --- ## 7. 2026 AHA/ACC Acute PE Clinical Categories The new classification is designed to connect bedside severity directly to disposition and therapy. [1,3] | Category | Clinical picture | Key objective features | Typical disposition/implication | |---|---|---|---| | **A** | Subclinical/incidental, asymptomatic PE | No PE symptoms | Usually outpatient if no separate reason for admission | | **B** | Symptomatic, low clinical severity | Low PESI/sPESI/Hestia profile | Early discharge/outpatient treatment often appropriate | | **C1** | Symptomatic, elevated clinical severity | Normal RV and normal cardiac biomarkers | Hospitalization; anticoagulation | | **C2** | Symptomatic, elevated severity | RV abnormality **or** ≥1 abnormal cardiac biomarker | Hospitalization; closer monitoring | | **C3** | Symptomatic, elevated severity | RV abnormality **and** ≥1 abnormal cardiac biomarker | Higher deterioration risk; monitored care/PERT consideration | | **D1** | Incipient cardiopulmonary failure | Transient/recurrent hypotension or relative hypotension without established end-organ hypoperfusion | High-acuity monitored care; advanced therapy may be considered | | **D2** | Incipient failure with hypoperfusion | Transient/relative hypotension plus end-organ hypoperfusion such as lactate >2 mmol/L, AKI, oliguria, mental-status change, low cardiac index/MAP | Critical-care level; PERT; advanced reperfusion consideration | | **E1** | Cardiopulmonary failure | Persistent/recurrent hypotension with cardiogenic shock | Advanced therapy is generally reasonable if feasible | | **E2** | Refractory failure / arrest | Refractory shock or cardiac arrest | Resuscitation, systemic lysis when appropriate, ECMO/advanced rescue in expert centers | #### Respiratory modifier “R” The 2026 system adds an **R modifier** when significant respiratory compromise is present. In Category C this includes features such as SpO₂ <90%, RR ≥30/min, or supplemental oxygen requirement; more advanced categories use higher oxygen/ventilatory support thresholds. [1,3] #### Why this is better than “massive/submassive” The older terminology can hide important gradients. A normotensive patient with RV dysfunction, positive troponin, lactate 4 mmol/L, oliguria, and escalating oxygen needs is much sicker than another normotensive patient with mild RV dilation alone. The A–E framework explicitly identifies that difference. --- ## 8. PESI, sPESI, and Hestia ### 8.1 PESI/sPESI These scores estimate short-term mortality and are most helpful when considering outpatient management. A **sPESI of 0** identifies a low-risk group when other outpatient criteria are satisfied. ### 8.2 Hestia criteria Hestia is a pragmatic exclusion checklist for outpatient treatment, incorporating hemodynamic instability, oxygen requirement, bleeding risk, severe pain needing IV medication, renal/liver failure, pregnancy, social barriers, and other practical concerns. **Important:** A low PESI/sPESI does not override clinical judgment, RV dysfunction, active bleeding, inability to obtain medication, severe comorbidity, or inadequate follow-up. --- ## 9. Acute management algorithm ```text Suspected PE ↓ Is patient in shock / peri-arrest? ├─ Yes → ABC resuscitation + bedside echo if useful + urgent CTPA if feasible │ → therapeutic anticoagulation if not contraindicated │ → PERT / ICU / interventional / surgical activation │ → consider immediate reperfusion strategy └─ No ↓ Estimate pretest probability ↓ Very low risk + all PERC negative? ├─ Yes → PE ruled out without D-dimer └─ No ↓ Low/intermediate probability → D-dimer strategy ├─ Negative → PE excluded └─ Positive → CTPA (or V/Q) High probability → proceed directly to imaging ↓ PE confirmed ↓ Anticoagulate unless contraindicated ↓ Risk stratify: PESI/sPESI/Hestia + RV + troponin/BNP + lactate + BP/perfusion + oxygen ↓ A/B → outpatient/early discharge when safe C → hospitalize; monitor intensity by C1/C2/C3 + R D → critical/step-down care + PERT; consider advanced reperfusion E → shock/arrest pathway; advanced reperfusion ± VA-ECMO in expert center ``` --- ## 10. Anticoagulation — STANDARD OF CARE Unless there is an absolute contraindication, **therapeutic anticoagulation should be initiated for acute PE** to reduce recurrence and death. [1] ### 10.1 Initial parenteral anticoagulation When parenteral therapy is required, the 2026 guideline recommends **LMWH over UFH** for most patients in Categories C1–E1 because LMWH reduces recurrent VTE and major bleeding. [1] #### When UFH can still be advantageous UFH is often selected when: - an immediate invasive procedure or thrombolysis is likely and rapid titration/reversal is desired; - severe renal dysfunction limits LMWH use; - extremely unstable physiology requires a highly controllable infusion; - local advanced-therapy protocols specify UFH. Do not treat “UFH for every high-risk PE” as a universal rule; the 2026 guideline explicitly prefers LMWH when parenteral therapy is required in most eligible patients. [1] ### 10.2 DOACs For eligible adults, **DOACs are recommended over vitamin K antagonists**. [1] Common evidence-based VTE regimens: [4] | Drug | Initial phase | Primary treatment | |---|---|---| | **Apixaban** | 10 mg PO twice daily for 7 days | 5 mg PO twice daily | | **Rivaroxaban** | 15 mg PO twice daily with food for 21 days | 20 mg PO once daily with food | | **Dabigatran** | Requires ≥5 days of parenteral anticoagulation first | 150 mg PO twice daily | | **Edoxaban** | Requires ≥5 days of parenteral anticoagulation first | 60 mg PO once daily in standard eligible patients | **Safety note:** renal function, hepatic function, age, weight, drug interactions, bleeding risk, and product-specific labeling must be checked before prescribing. Edoxaban and other agents have label-defined dose modifications that should not be guessed from memory. #### 2026 comparative evidence The COBRRA randomized trial compared apixaban with rivaroxaban for acute VTE and found clinically relevant bleeding at 3 months in **3.3% vs 7.1%**, respectively, with similar VTE efficacy. The 2026 ACC scientific statement therefore suggests apixaban may be preferred for many patients when either agent is otherwise suitable. This is an evolving comparative-practice consideration rather than a declaration that rivaroxaban is inappropriate. [4,18] ### 10.3 Empiric anticoagulation before imaging If PE is strongly suspected, imaging is delayed, and bleeding risk is low, the 2026 guideline states that therapeutic anticoagulation may be beneficial in patients with a clinical picture equivalent to **Category C2 or higher**. [1] This is not an excuse to anticoagulate every low-probability patient before diagnosis. --- ## 11. Reperfusion and advanced therapies The central decision is whether anticoagulation alone is sufficient or whether clot removal/lysis is needed because the RV is failing or likely to fail. ### 11.1 Systemic thrombolysis #### Standard regimen The most commonly used FDA-approved alteplase regimen for PE is: **Alteplase 100 mg IV over 2 hours.** [1] Lower-dose systemic regimens may be considered in selected circumstances to reduce bleeding, but evidence is less robust and protocols vary. [1] #### Who should receive systemic thrombolysis? | 2026 category | Systemic lysis position | |---|---| | A–C1 | **Harm / do not use routinely** | | C2 | **Harm / do not use routinely** | | C3 | Benefit uncertain; highly individualized if advanced therapy is contemplated | | D1–D2 | May be considered with acceptable bleeding risk | | E1–E2 | Reasonable when advanced reperfusion is indicated and bleeding risk is acceptable | This explains a classic board principle: **routine fibrinolysis for a normotensive intermediate-risk PE is not standard care**. The PEITHO trial reduced hemodynamic decompensation but increased major extracranial bleeding and hemorrhagic stroke with systemic tenecteplase, without a mortality advantage sufficient to justify routine use. [7] ### 11.2 Catheter-directed thrombolysis (CDT) The 2026 guideline position, based largely on pre-2025 evidence, is: [1,3] - **E1:** CDT + anticoagulation is reasonable. - **D1–D2:** may be considered when advanced therapy is being considered. - **C2–C3:** benefit vs anticoagulation alone was considered uncertain. - **A–C1:** routine catheter intervention has no benefit. This field changed materially after the evidence cutoff; see HI-PEITHO and PRAGUE-26 below. ### 11.3 Mechanical thrombectomy For catheter-based mechanical thrombectomy (MT): [1] - **E1:** reasonable compared with anticoagulation alone. - **D1–D2:** may be considered. - **C2–C3:** benefit remains uncertain for routine use. - A–C1: not routinely beneficial. A major attraction is avoiding or minimizing thrombolytic exposure, but access-site bleeding, pulmonary-artery injury, blood loss, procedural deterioration, and device-specific complications remain possible. ### 11.4 Surgical embolectomy Surgical embolectomy is reasonable in **E1** and may be considered in selected **D1–D2** patients, especially when thrombolysis is contraindicated or has failed and surgical expertise is immediately available. [1] It can also be attractive for: - central clot burden with shock; - right-heart clot-in-transit; - selected patients with a patent foramen ovale and systemic embolic risk; - situations where catheter options are unsuitable. ### 11.5 Right-heart clot-in-transit A free-floating right-atrial/RV thrombus is uncommon but high risk. In Categories C3–E2, the 2026 guideline considers advanced therapy reasonable over anticoagulation alone to reduce deterioration, although randomized comparative evidence is limited. [1] ### 11.6 VA-ECMO **Venoarterial extracorporeal membrane oxygenation (VA-ECMO)** can provide circulatory/oxygenation support in refractory cardiogenic shock or arrest from PE in expert centers. It is usually a bridge to recovery or definitive reperfusion, not treatment of the clot itself. [1] --- ## 12. Hemodynamic and respiratory support ### 12.1 Oxygen and ventilation Correct hypoxemia while avoiding interventions that precipitate RV collapse. Positive-pressure ventilation can reduce venous return and increase RV afterload. In a tenuous PE patient, deep sedation and intubation may trigger sudden cardiovascular collapse. If intubation is unavoidable: - involve experienced airway/critical-care staff; - optimize preload and vasopressor support before induction; - use hemodynamically cautious induction; - minimize excessive PEEP/airway pressures while maintaining adequate oxygenation. ### 12.2 Fluids The failing RV is preload-sensitive but easily overdistended. Large indiscriminate fluid boluses can worsen septal shift and cardiac output. Use **small, reassessed fluid challenges** only when true preload deficiency is plausible. Stop if JVP/RV dilation worsens without improved perfusion. ### 12.3 Vasopressors/inotropes In obstructive shock, vasopressor support is often required to restore systemic pressure and RV coronary perfusion while definitive reperfusion is arranged. Norepinephrine is commonly favored in shock physiology; inotropes may be added for severe low-output RV failure under critical-care guidance. The goal is not simply a numeric blood pressure—it is restoration of **organ perfusion** without excessive tachycardia or RV oxygen demand. --- ## 13. Disposition ### Category A The 2026 guideline states that asymptomatic Category A patients can generally be discharged rather than hospitalized, assuming no competing reason for admission and a safe treatment/follow-up plan. [1,3] ### Category B Early discharge/outpatient treatment is generally recommended if: - low PESI/sPESI/Hestia risk; - no oxygen/hemodynamic instability; - no major bleeding risk; - reliable access to anticoagulation; - adequate home support and follow-up. ### Categories C–E Hospitalization is recommended because of increasing deterioration risk. Level of care escalates with: - C3 physiology; - respiratory modifier; - lactate/end-organ hypoperfusion; - transient hypotension; - escalating oxygen; - shock/arrest. --- ## 14. Duration of anticoagulation The 2026 guideline defines: - **Initial treatment phase:** first **3–6 months**. - **Extended phase:** beyond 6 months. [1] ### 14.1 Major reversible provoking factor If a first PE occurred because of a **major reversible risk factor** and that factor has resolved, stopping anticoagulation after the initial treatment phase is generally recommended when recurrence risk is low and there is no other indication for continued therapy. [1] ### 14.2 No major reversible factor / unprovoked PE Extended anticoagulation is recommended for many patients after a first PE without a major reversible risk factor, assuming bleeding risk is acceptable. [1] ### 14.3 Persistent risk factor Continued anticoagulation is generally recommended while a clinically important persistent risk factor remains, with periodic reassessment. ### 14.4 Extended-dose options Evidence-supported extended regimens include: [4] - **Apixaban 2.5 mg twice daily** after completion of primary therapy in selected patients. - **Rivaroxaban 10 mg once daily** in selected patients. - Full-dose regimens remain appropriate in patients with higher recurrence risk. Duration is a shared decision balancing recurrence risk, bleeding risk, comorbidity, preference, cost, adherence, and changing life circumstances. --- ## 15. Special populations ### 15.1 Pregnancy Pregnancy changes both diagnostic and treatment decisions. - Pregnancy-adapted YEARS can reduce imaging in appropriate patients. - **LMWH is generally preferred** for treatment during pregnancy. - UFH may be useful close to delivery or when rapid reversibility is needed. - DOACs should not be used routinely in pregnancy and are generally avoided during breastfeeding because of insufficient safety data. - Warfarin is teratogenic and is generally avoided during pregnancy, although there are narrow specialist-managed exceptions in mechanical-valve care unrelated to routine PE treatment. A pregnant patient with shock from PE requires immediate multidisciplinary maternal resuscitation; maternal survival is the priority. ### 15.2 Cancer-associated PE DOACs or LMWH are effective. Choice depends on: - bleeding risk, particularly GI/GU mucosal tumors; - thrombocytopenia; - drug interactions; - vomiting/malabsorption; - renal function; - planned procedures; - patient preference. The 2026 ACC statement notes a strong evidence base for apixaban in cancer-associated thrombosis, while LMWH remains valuable in high-bleeding-risk or interaction-heavy situations. [4] ### 15.3 Antiphospholipid syndrome For thrombotic APS—especially high-risk/triple-positive APS—**vitamin K antagonist therapy is generally preferred over DOACs** because DOACs have been associated with excess recurrent arterial/thrombotic events in high-risk APS. ### 15.4 Severe renal disease Renal clearance differs substantially among DOACs. Severe CKD/dialysis requires drug-specific labeling and specialist judgment; do not apply standard VTE doses automatically. UFH or carefully selected anticoagulant strategies may be preferable in some patients. ### 15.5 Liver disease Hepatic dysfunction affects both coagulation and DOAC metabolism. The 2026 ACC statement supports individualized use by Child-Pugh class and notes that evidence becomes very limited in severe hepatic disease. [4] ### 15.6 Isolated subsegmental PE Management is individualized. Important questions include: - Is the diagnosis radiographically certain? - Is there proximal DVT? - Is the patient pregnant, has active cancer, prior VTE, impaired cardiopulmonary reserve, or persistent provoking risk? - Is the patient symptomatic? - Can reliable surveillance be performed? Selected low-risk patients with isolated subsegmental PE and no DVT may be candidates for surveillance in some guidelines, but many patients have enough recurrence risk to favor anticoagulation. This requires careful shared decision-making rather than an automatic rule. [17] --- ## 16. Complications | Complication | Clinical clues | Management principle | |---|---|---| | Obstructive shock | Hypotension, cool skin, oliguria, lactate rise, confusion | Vasopressor support + urgent reperfusion strategy | | Cardiac arrest | Often PEA | CPR + high suspicion; systemic lysis/ECMO/advanced reperfusion as appropriate | | Recurrent PE | New dyspnea/chest pain/syncope while treated | Verify adherence/dose/interactions; repeat imaging; consider alternate anticoagulant class | | Major bleeding | GI, intracranial, retroperitoneal, access-site | Stop/reverse anticoagulation as appropriate; hemostasis; reassess thrombosis risk | | Chronic thromboembolic pulmonary disease | Persistent dyspnea/exercise intolerance ≥3 months | Structured evaluation; V/Q often central to CTEPD workup; refer expert center | | CTEPH | Persistent pulmonary hypertension from chronic organized thrombi | Expert-center evaluation for endarterectomy/BPA/medical therapy | | Post-PE syndrome | Dyspnea, reduced exercise capacity despite no CTEPH | Exclude CTEPD, cardiac/pulmonary disease; rehabilitation and targeted management | --- ## 17. Follow-up after acute PE The acute event is not over at discharge. The 2026 guideline recommends: [1,3] - early post-discharge contact/assessment can be helpful, often within the first week; - a clinical visit **by about 3 months** to assess symptoms, bleeding, adherence, provoking factors, and anticoagulation duration; - asking about **dyspnea and functional limitation for at least 1 year** after PE; - evaluating persistent symptoms after ≥3 months of anticoagulation for CTEPD/CTEPH or other causes. #### Follow-up checklist - Confirm anticoagulant and correct dose. - Check renal/hepatic function when relevant. - Review bleeding and interacting medications. - Clarify whether the PE was major-provoked, minor-provoked, persistent-risk, or unprovoked. - Decide initial vs extended anticoagulation plan. - Encourage safe early ambulation. - Review cancer screening based on age/standard indications rather than indiscriminate extensive testing. - Ask about exertional dyspnea, exercise intolerance, chest pain, syncope, edema. --- ## 18. Common pitfalls | Pitfall | Why it is dangerous | Better approach | |---|---|---| | Ordering D-dimer in a high-probability patient | Delays definitive imaging and is likely positive | Proceed directly to imaging | | Using PERC in moderate-risk patients | PERC was designed for very-low pretest probability | Estimate probability first | | Treating saddle location as synonymous with “massive PE” | Anatomy ≠ physiology | Risk-stratify by BP, perfusion, RV function, biomarkers, respiratory status | | Calling a normotensive patient “stable” despite lactate/AKI | Misses normotensive shock | Assess end-organ perfusion and Category D physiology | | Giving liters of crystalloid for RV shock | Can overdistend RV and reduce LV filling | Small, reassessed bolus only if preload-responsive; vasopressors/reperfusion early | | Intubating a tenuous PE patient without hemodynamic preparation | Induction/positive pressure can precipitate arrest | Optimize pressors/preload; expert airway strategy | | Routine systemic lysis in intermediate-risk PE | Major bleeding/ICH risk | Anticoagulation + monitoring; select advanced therapy by deterioration risk | | Assuming all catheter devices have equal RCT evidence | Devices/mechanisms differ | Apply trial data only to comparable technology/populations | | Stopping anticoagulation automatically at 3 months | Recurrence risk may remain high | Reassess provoking/persistent factors and bleeding risk | | Ignoring persistent dyspnea after PE | Misses CTEPD/CTEPH | Structured follow-up for at least a year | --- ## 19. Acute management checklist ### First 10–30 minutes - [ ] ABC assessment; identify shock/arrest. - [ ] Oxygen as needed; avoid unplanned deep sedation/intubation in RV failure. - [ ] IV access, ECG, continuous monitoring. - [ ] Determine pretest probability if diagnosis is not established. - [ ] PERC only if truly very low risk. - [ ] D-dimer if low/intermediate probability and appropriate. - [ ] CTPA or V/Q when indicated. - [ ] If confirmed: assess BP trend, oxygen requirement, RV, troponin/BNP, lactate, renal perfusion/mental status. - [ ] Start therapeutic anticoagulation unless contraindicated. ### After confirmation - [ ] Assign AHA/ACC category A–E ± respiratory modifier. - [ ] A/B: assess outpatient safety using PESI/sPESI/Hestia and social/bleeding factors. - [ ] C–E: hospitalize. - [ ] C3/D/E: early PERT/critical-care discussion. - [ ] D/E: prepare reperfusion strategy before deterioration becomes arrest. ### Shock pathway - [ ] Avoid excessive fluids. - [ ] Vasopressor support as needed. - [ ] Activate PERT/interventional/surgical teams. - [ ] Choose systemic thrombolysis vs CDT vs MT vs surgery based on category, bleeding risk, anatomy, timing, expertise. - [ ] Consider VA-ECMO in refractory shock/arrest in an experienced system. --- ## 20. Exam-focused review ### Foundation / Step 1 Know the physiology: **PE → ↑ pulmonary vascular resistance → RV dilation/failure → septal shift → ↓ LV preload → ↓ cardiac output → obstructive shock.** Understand Virchow’s triad and why tachycardia/hypoxemia arise. ### Step 2 CK High-yield sequence: - very-low probability + PERC negative → no testing; - low/intermediate probability → D-dimer; - high probability or positive D-dimer → imaging; - confirmed PE → anticoagulate and risk-stratify; - shock → reperfusion, not anticoagulation alone. ### Step 3 / resident Know: - age-adjusted D-dimer = age × 10 µg/L FEU after age 50 in validated pathways; - apixaban 10 mg BID ×7 days → 5 mg BID; - rivaroxaban 15 mg BID ×21 days → 20 mg daily; - dabigatran/edoxaban require ≥5 days initial parenteral anticoagulation; - systemic alteplase regimen commonly 100 mg over 2 hours; - LMWH is now guideline-preferred over UFH when initial parenteral therapy is needed in most eligible patients; - hemodynamic status plus RV/biomarkers/perfusion determines treatment—not clot size alone. ### MRCP/ABIM/board level Be able to distinguish: - low-risk PE vs C3 PE vs D2 normotensive shock; - thrombolysis indications vs contraindications; - outpatient eligibility vs admission; - recurrence-risk decisions for anticoagulation duration; - CTEPD/CTEPH follow-up; - guideline-standard advanced therapy vs post-guideline emerging CDT evidence. --- ## 21. Original MCQs #### Question 1 A 34-year-old woman with pleuritic chest pain has clinician-estimated PE probability <10%. HR 82, SpO₂ 98%, no hemoptysis, no estrogen use, no prior VTE, no unilateral swelling, no recent surgery/trauma. What is the best next step? A. CTPA B. D-dimer in all cases C. Apply PERC; if all negative, no further PE testing D. Start apixaban empirically **Answer: C.** PERC can exclude PE without D-dimer in genuinely very-low-risk patients when all criteria are negative. [1] #### Question 2 A 74-year-old low/intermediate-probability patient has D-dimer 650 µg/L FEU. Using a validated age-adjusted strategy, which statement is most accurate? A. The result is automatically positive because it exceeds 500 B. The age-adjusted cutoff is approximately 740 µg/L FEU C. The age-adjusted cutoff is 74 µg/L D. Age adjustment is used only below age 50 **Answer: B.** For age >50, a commonly validated FEU cutoff is age ×10 µg/L, here approximately 740. [1,5] #### Question 3 A patient has confirmed PE, normal BP, elevated sPESI, RV dilation, positive troponin, lactate 4 mmol/L, oliguria, and cool extremities. Which concept is most important? A. Normal BP proves low-risk PE B. This can represent normotensive shock/incipient cardiopulmonary failure C. Troponin proves acute MI rather than PE D. The patient should be discharged on a DOAC **Answer: B.** End-organ hypoperfusion can precede persistent hypotension; this is the rationale for Category D2 physiology in the 2026 scheme. [1,3] #### Question 4 Which anticoagulation statement is correct in the 2026 guideline? A. UFH is always preferred to LMWH in acute PE B. LMWH is recommended over UFH when initial parenteral therapy is required in most C1–E1 patients C. Warfarin is preferred over DOACs for most eligible adults D. Anticoagulation should wait until all thrombophilia tests return **Answer: B.** LMWH is guideline-preferred over UFH for most patients requiring initial parenteral therapy, and DOACs are preferred over VKAs when eligible. [1] #### Question 5 Which apixaban regimen is evidence-based for acute VTE in a standard eligible adult? A. 2.5 mg BID from day 1 B. 5 mg daily C. 10 mg BID for 7 days, then 5 mg BID D. 10 mg daily after 5 days of heparin **Answer: C.** [4,9] #### Question 6 A normotensive patient has elevated clinical severity score but normal RV function and normal cardiac biomarkers. Which 2026 category best fits? A. A B. B C. C1 D. E1 **Answer: C.** C1 is symptomatic PE with elevated clinical severity but normal RV and biomarkers. [1,3] #### Question 7 Which statement about systemic thrombolysis is most accurate? A. It is routine for all RV-strain PE B. It should be used for all C2 patients C. It is reasonable in cardiopulmonary failure when bleeding risk is acceptable, but routine use in A–C2 is discouraged because of bleeding/ICH D. It is contraindicated in cardiac arrest from PE **Answer: C.** The benefit-risk balance changes sharply as the patient progresses toward D/E physiology. [1] #### Question 8 Which statement best reflects the 2026 catheter-directed thrombolysis evidence? A. The February guideline already incorporated PRAGUE-26 B. HI-PEITHO and PRAGUE-26 were published after the guideline evidence cutoff and suggest reduced early deterioration in selected intermediate-risk patients C. Catheter treatment is now mandatory for every C3 patient D. All catheter devices are clinically interchangeable **Answer: B.** The trials are important emerging evidence but require careful population/device-specific interpretation. [1,15,16] --- ## 22. Current guideline changes and recent research ### STANDARD OF CARE — 2026 multisociety guideline #### New A–E severity categories The 2026 guideline’s most visible conceptual change is replacement of broad low/intermediate/high-risk terminology with categories that integrate symptoms, clinical severity scores, RV function, biomarkers, respiratory compromise, transient hypotension, and end-organ perfusion. [1,3] #### PERT Multidisciplinary PERT assessment is recommended for patients at increased risk of adverse outcomes (Categories C–E) to improve care delivery. [1,3] #### Anticoagulation - LMWH over UFH when parenteral therapy is required in most eligible patients. - DOAC over VKA for most eligible patients. - Extended anticoagulation for first PE without a major reversible factor and for persistent risk factors when bleeding risk permits. [1] #### Advanced therapy - **E1:** systemic thrombolysis, CDT, MT, and surgical embolectomy are reasonable options depending on patient/center factors. - **D1–D2:** these therapies may be considered. - **A–C2:** routine systemic thrombolysis is harmful; routine advanced catheter/surgical treatment is not supported. - **C3:** evidence for routine advanced reperfusion remained uncertain in the guideline. [1,3] #### Follow-up Screen for post-PE symptoms and functional limitation for at least one year; evaluate persistent dyspnea for CTEPD/CTEPH. [1,3] --- ### EMERGING EVIDENCE — HI-PEITHO (2026) HI-PEITHO randomized **544** selected intermediate-risk PE patients with RV/LV ratio ≥1.0, elevated troponin, and at least two indicators of cardiorespiratory distress to ultrasound-facilitated catheter-directed fibrinolysis plus anticoagulation or anticoagulation alone. [15] The primary composite of PE-related death, cardiorespiratory decompensation/collapse, or symptomatic recurrent PE occurred in **4.0% vs 10.3%**. The benefit was driven mainly by less clinical deterioration; major bleeding was numerically higher but not statistically different, and no intracranial hemorrhage occurred in either group. [15] #### Interpretation This trial lowers the threshold for discussing CDT in **carefully selected higher-severity normotensive PE**, but it does not prove that every patient with RV strain should undergo an intervention. The population was highly selected, and results should not be generalized to every catheter device or lower-risk PE. [15] --- ### EMERGING EVIDENCE — PRAGUE-26 (published August 31, 2026) PRAGUE-26 randomized **558** patients with intermediate-high-risk PE to catheter-directed alteplase thrombolysis plus anticoagulation or anticoagulation alone. [16] The 7-day composite of death, recurrent PE, or cardiorespiratory decompensation/collapse occurred in: - **0.7%** with catheter-directed thrombolysis - **6.8%** with standard care - RR **0.10** (95% CI 0.02–0.44; P<0.001). [16] The difference was again driven largely by prevention of decompensation. Clinically relevant bleeding was similar (**4.6% vs 5.0%**); major bleeding was **1.4% vs 2.2%**; intracranial hemorrhage occurred in **0.7% vs 0%**. [16] #### Why this matters PRAGUE-26 was published **after** the February 2026 guideline and therefore is not incorporated into its formal recommendations. Along with HI-PEITHO, it substantially strengthens the clinical-outcome evidence for selected catheter-directed thrombolysis in intermediate-high-risk PE. #### What it does not prove - It does not establish catheter treatment as mandatory for all intermediate-risk PE. - It does not establish equivalence across all devices, lytic doses, or center expertise. - It does not eliminate intracranial or major bleeding risk. - Mortality benefit remains less certain than reduction in deterioration. A future guideline update may change the formal category-C recommendations. --- ### EXPERIMENTAL / INVESTIGATIONAL Areas still requiring stronger evidence include: - selecting the exact C2/C3 phenotype that gains net benefit from early catheter intervention; - head-to-head CDT vs mechanical thrombectomy; - optimal lytic dose and device strategy; - validated biomarkers of impending RV collapse; - long-term effects of acute catheter therapy on post-PE syndrome/CTEPH; - artificial-intelligence–assisted CT triage without compromising clinical judgment. --- ## 23. Guideline differences: 2019 ESC vs 2026 AHA/ACC The 2019 ESC guideline stratifies PE as low risk, intermediate-low, intermediate-high, or high risk using hemodynamic status, PESI/sPESI, RV dysfunction, and troponin. [8] The 2026 AHA/ACC system maps broadly as follows: [3] | 2019 ESC concept | Approximate 2026 AHA/ACC counterpart | |---|---| | Low risk | B (and some A) | | Intermediate-low | C1–C2 | | Intermediate-high | C3 | | Hemodynamic instability/high risk | D–E, with greater granularity for transient hypotension, normotensive shock, established shock, and arrest | They are not perfectly interchangeable. The 2026 model explicitly emphasizes **end-organ perfusion and respiratory modifiers**, allowing earlier recognition of impending failure. --- ## 24. References 1. Creager MA, Barnes GD, Giri J, et al. **2026 AHA/ACC/ACCP/ACEP/CHEST/SCAI/SHM/SIR/SVM/SVN Guideline for the Evaluation and Management of Acute Pulmonary Embolism in Adults.** *J Am Coll Cardiol*. 2026;87(13):1626-1710. doi: **10.1016/j.jacc.2025.11.005**. https://www.jacc.org/doi/10.1016/j.jacc.2025.11.005 2. **Correction: 2026 Acute Pulmonary Embolism Guideline.** *J Am Coll Cardiol*. 2026;88(6):713. Published August 11, 2026. doi: **10.1016/j.jacc.2026.06.033**. https://www.jacc.org/doi/10.1016/j.jacc.2026.06.033 3. Dudzinski DM, Cibotti-Sun M, Moore MM. **2026 Acute Pulmonary Embolism Guideline-at-a-Glance.** *J Am Coll Cardiol*. 2026;87(13):1620-1625. doi: **10.1016/j.jacc.2025.12.023**. 4. Kumbhani DJ, Armbruster AL, Cheng RK, et al. **Direct Oral Anticoagulants in Primary and Secondary Prevention of Thrombotic Events: 2026 ACC Scientific Statement.** *J Am Coll Cardiol*. 2026. doi: **10.1016/j.jacc.2026.05.033**. 5. Righini M, Van Es J, Den Exter PL, et al. **Age-Adjusted D-Dimer Cutoff Levels to Rule Out Pulmonary Embolism: The ADJUST-UNLIKELY/ADJUST-PE strategy evidence.** *JAMA*. 2014;311:1117-1124. doi: **10.1001/jama.2014.2135**. 6. van der Hulle T, Cheung WY, Kooij S, et al. **Simplified diagnostic management of suspected pulmonary embolism (the YEARS study).** *Lancet*. 2017;390:289-297. doi: **10.1016/S0140-6736(17)30885-1**. 7. Meyer G, Vicaut E, Danays T, et al. **Fibrinolysis for Patients with Intermediate-Risk Pulmonary Embolism (PEITHO).** *N Engl J Med*. 2014;370:1402-1411. doi: **10.1056/NEJMoa1302097**. 8. Konstantinides SV, Meyer G, Becattini C, et al. **2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism developed in collaboration with the ERS.** *Eur Heart J*. 2020;41:543-603. doi: **10.1093/eurheartj/ehz405**. 9. Agnelli G, Buller HR, Cohen A, et al. **Oral Apixaban for the Treatment of Acute Venous Thromboembolism (AMPLIFY).** *N Engl J Med*. 2013;369:799-808. doi: **10.1056/NEJMoa1302507**. 10. EINSTEIN–PE Investigators. **Oral Rivaroxaban for the Treatment of Symptomatic Pulmonary Embolism.** *N Engl J Med*. 2012;366:1287-1297. doi: **10.1056/NEJMoa1113572**. 11. Schulman S, Kearon C, Kakkar AK, et al. **Dabigatran versus Warfarin in the Treatment of Acute Venous Thromboembolism.** *N Engl J Med*. 2009;361:2342-2352. doi: **10.1056/NEJMoa0906598**. 12. Hokusai-VTE Investigators. **Edoxaban versus Warfarin for the Treatment of Symptomatic Venous Thromboembolism.** *N Engl J Med*. 2013;369:1406-1415. doi: **10.1056/NEJMoa1306638**. 13. Stevens SM, Woller SC, Kreuziger LB, et al. **Antithrombotic Therapy for VTE Disease: Second Update of the CHEST Guideline and Expert Panel Report.** *Chest*. 2021;160:e545-e608. doi: **10.1016/j.chest.2021.07.055**. 14. Kearon C, Akl EA, Ornelas J, et al. **Antithrombotic Therapy for VTE Disease: CHEST Guideline and Expert Panel Report.** *Chest*. 2016;149:315-352. doi: **10.1016/j.chest.2015.11.026**. 15. Rosenfield K, Klok FA, Piazza G, et al; HI-PEITHO Investigators. **Ultrasound-Facilitated, Catheter-Directed Fibrinolysis for Acute Pulmonary Embolism.** *N Engl J Med*. 2026;394(20):1979-1990. doi: **10.1056/NEJMoa2516567**. PMID: **41910345**. 16. Clarençon F, et al. **Catheter-Directed Thrombolysis in Intermediate-High-Risk Pulmonary Embolism (PRAGUE-26).** *N Engl J Med*. Published August 31, 2026. doi: **10.1056/NEJMoa2608012**. 17. Piazza G, et al. **Extended-Duration Low-Intensity Apixaban to Prevent Recurrence in High-Risk Patients With Provoked Venous Thromboembolism (HI-PRO).** *N Engl J Med*. 2025. See ACC ESC 2025 report for trial details. 18. Castellucci LA, Chen VM, Kovacs MJ, et al. **Bleeding Risk with Apixaban vs Rivaroxaban in Acute Venous Thromboembolism (COBRRA).** *N Engl J Med*. 2026;394(11):1051-1060. doi: **10.1056/NEJMoa2510703**. 19. Piazza G, Cushman M. **AHA/ACC Acute Pulmonary Embolism Clinical Categories: Perspectives on Development and Application.** *J Am Coll Cardiol*. 2026;87(13):1554-1557. doi: **10.1016/j.jacc.2025.11.053**. --- ### Bottom line The modern approach to PE is not “diagnose clot and give anticoagulation.” It is a sequence of **probability-based diagnosis, immediate anticoagulation when appropriate, and rapid physiologic risk stratification of the right ventricle and systemic perfusion**. The 2026 AHA/ACC categories make a critical distinction between compensated RV strain and **incipient cardiopulmonary failure**, where early escalation may prevent arrest. Anticoagulation remains the foundation of treatment; advanced reperfusion is standard in shock-level disease and increasingly evidence-supported in carefully selected higher-risk normotensive patients, but treatment must remain individualized to bleeding risk, physiology, anatomy, and local expertise.1c:Tebc2,## One-minute summary **Atrial fibrillation (AF)** is a supraventricular tachyarrhythmia characterized by chaotic atrial electrical activation and ineffective atrial contraction. On ECG it produces **irregularly irregular RR intervals** (when AV conduction is intact), absence of discrete organized P waves, and fibrillatory atrial activity. A standard 12-lead ECG can establish the diagnosis; ambulatory/device tracings require clinician-confirmed electrocardiographic evidence rather than pulse irregularity alone.[1,2] AF management has four simultaneous goals. The **2024 ESC AF-CARE pathway** organizes them as: **[C] Comorbidity and risk-factor management; [A] Avoid stroke and thromboembolism; [R] Reduce symptoms with rate and rhythm control; [E] Evaluate and dynamically reassess.**[2] ### Immediate priorities 1. **Is the patient hemodynamically unstable because of AF?** If yes, perform urgent synchronized electrical cardioversion; do not delay a life-saving shock for a prolonged anticoagulation workup.[1,2] 2. **If stable, identify and treat precipitants** such as sepsis, hypovolemia, acute coronary syndrome, pulmonary embolism, hypoxia, hyperthyroidism, electrolyte disturbance, alcohol excess, or decompensated heart failure. 3. Choose **rate control, rhythm control, or both**, based on symptoms, AF duration, ventricular function, comorbidity, age, patient preference, and the potential prognostic benefit of early rhythm control.[1,2,8] 4. Assess **stroke risk independently of apparent rhythm success.** In the 2023 ACC/AHA/ACCP/HRS guideline, anticoagulation is recommended when estimated annual thromboembolic risk is ≥2% (roughly CHA₂DS₂-VASc ≥2 in men or ≥3 in women) and is reasonable at 1–2%/year.[1] The 2024 ESC guideline instead uses **CHA₂DS₂-VA** (sex removed): anticoagulation should be considered at 1 and is recommended at ≥2.[2] 5. **DOACs are preferred to warfarin** in eligible patients, except for mechanical heart valves and clinically significant mitral stenosis where a vitamin K antagonist remains standard.[1,2] ### Major 2024–2026 practice points - ESC 2024 **reduced the known-duration threshold for un-anticoagulated early cardioversion from 48 to 24 hours**. If AF is known to have lasted >24 h, ESC recommends ≥3 weeks therapeutic anticoagulation or transesophageal echocardiography (TOE/TEE) to exclude thrombus before elective cardioversion.[2,3] - The 2023 US guideline retains a **≥48-hour** threshold for a Class I requirement for 3 weeks of uninterrupted anticoagulation or imaging before elective cardioversion, while also emphasizing that risk is continuous and depends on patient substrate rather than duration alone.[1] - Catheter ablation is no longer simply a “last resort.” It is a first-line rhythm-control option in selected symptomatic patients, especially paroxysmal AF; it has particularly important outcome data in AF with HFrEF.[1,2,10] - Device-detected subclinical AF is **not automatically equivalent** to clinical AF. ARTESiA showed fewer strokes/systemic emboli with apixaban but more major bleeding, whereas NOAH-AFNET 6 found no significant efficacy advantage for edoxaban and more harm on a composite safety outcome.[11,12] - New **2026 AHA/ACC AF performance and quality measures** reinforce annual validated stroke-risk assessment, appropriate DOAC use, risk-factor modification, shared decision-making, and rhythm-control consideration in HFrEF.[13] --- ## Core concepts ### Why AF matters AF is not merely an irregular pulse. Its clinical consequences arise from several interacting mechanisms: - **loss of coordinated atrial contraction** → reduced ventricular filling, especially important in stiff ventricles; - **rapid or irregular ventricular response** → impaired cardiac output and possible tachycardia-induced cardiomyopathy; - **atrial stasis and endothelial dysfunction**, particularly in the left atrial appendage (LAA) → thrombus formation and embolic stroke; - **atrial remodeling** → electrical and structural changes that promote persistence (“AF begets AF”); - **shared disease substrate** with hypertension, obesity, sleep apnea, diabetes, CKD, heart failure, vascular disease, and aging. AF is the most common sustained arrhythmia in clinical practice. Contemporary US data cited by the 2026 AHA/ACC measures estimate more than **10.5 million US adults** carry an AF diagnosis and lifetime risk approaches **1 in 3**.[13] --- ## Definition and electrocardiographic diagnosis ### ECG features Typical AF shows: - irregularly irregular ventricular rhythm; - no consistent P waves; - variable fibrillatory baseline activity; - usually narrow QRS unless pre-existing bundle-branch block, rate-related aberrancy, ventricular pacing, or pre-excitation is present. A regular rhythm argues against ordinary AF and should prompt reconsideration (e.g., atrial flutter with fixed conduction, paced rhythm, junctional rhythm, AV block). #### Confirm the rhythm Consumer wearables, photoplethysmography, automated cuff alerts, and implantable devices are useful for screening and surveillance, but **a clinical AF diagnosis requires reviewable electrocardiographic evidence**. The 2024 ESC guideline accepts a 12-lead ECG or sufficiently clear ambulatory ECG evidence; older research definitions commonly use episodes ≥30 seconds, although management decisions should consider the clinical context and AF burden rather than treating “30 seconds” as a biologic cliff.[2] --- ## Classification ### Conventional temporal classification | AF pattern | Definition | Clinical implication | |---|---|---| | **First diagnosed AF** | First documented episode, regardless of duration | Does not imply mechanism or future course | | **Paroxysmal AF** | Terminates spontaneously or with intervention within 7 days | Often more amenable to early rhythm control/ablation | | **Persistent AF** | Sustained >7 days | Greater atrial remodeling; cardioversion often required | | **Long-standing persistent AF** | Continuous AF >12 months when rhythm control remains pursued | Lower rhythm-control success; careful selection needed | | **Permanent AF** | Patient and clinician accept AF and no longer pursue sinus rhythm | A treatment decision, not an irreversible electrophysiologic state | ### 2023 ACC/AHA disease-stage framework The US guideline reframed AF as a progressive disease continuum:[1] - **Stage 1 — At risk:** risk factors present but no structural/electrical findings. - **Stage 2 — Pre-AF:** structural/electrical findings that predispose to AF but no prior AF episode. - **Stage 3 — AF:** includes paroxysmal, persistent, long-standing persistent, and patients after successful ablation. - **Stage 4 — Permanent AF:** decision made not to pursue further rhythm-control attempts. **Why this matters:** prevention and risk-factor treatment begin *before* AF becomes persistent. --- ## Epidemiology and risk factors AF prevalence rises sharply with age and is strongly associated with accumulated cardiovascular risk. Important modifiable and nonmodifiable contributors include: #### Cardiovascular - hypertension; - coronary artery disease / prior MI; - heart failure (HFrEF or HFpEF); - valvular disease, especially mitral disease; - cardiomyopathy; - congenital heart disease; - atrial enlargement; - cardiac surgery. #### Metabolic / systemic - increasing age; - obesity; - diabetes mellitus; - chronic kidney disease; - hyperthyroidism; - systemic inflammation/sepsis; - pulmonary disease and hypoxemia; - pulmonary embolism; - obstructive sleep apnea. #### Lifestyle / exposures - heavy alcohol use and binge drinking (“holiday heart”); - smoking; - physical inactivity; - extreme endurance exercise in some individuals; - stimulant/drug exposure in selected cases. #### Genetic / familial Familial AF and pathogenic variants can occur, particularly in early-onset disease. In unusually young patients without conventional risk factors, consider inherited cardiomyopathy/channelopathy or an accessory pathway depending on phenotype. --- ## Pathophysiology ### Trigger + substrate model Most AF requires both: 1. **Triggers**, commonly rapidly firing foci from the pulmonary veins; and 2. **A vulnerable atrial substrate**, produced by fibrosis, dilation, inflammation, autonomic changes, cellular calcium-handling abnormalities, and conduction heterogeneity. Repeated AF itself promotes: - shortening of atrial refractory periods; - calcium-handling changes; - fibrosis and atrial dilation; - loss of effective contractility. This explains why early rhythm control and aggressive risk-factor treatment can be more successful before long-standing remodeling develops. ### Stroke mechanism Thromboembolism is driven by a Virchow-triad-like interaction: - atrial/LAA blood stasis; - endothelial/endocardial dysfunction; - prothrombotic systemic state. Most AF-related cardiac thrombi form in the LAA, which is why LAA occlusion/exclusion strategies exist. However, AF also marks a broader **atrial cardiomyopathy and vascular-risk phenotype**, helping explain why stroke risk does not disappear immediately when sinus rhythm is restored. ### Tachycardia-/arrhythmia-induced cardiomyopathy Persistent rapid AF can cause or worsen LV systolic dysfunction. Clues include: - newly reduced LVEF without another clear cause; - high AF burden / sustained tachycardia; - substantial LVEF improvement after rhythm control. This is an especially important population because rhythm control—often catheter ablation—may improve ventricular function and clinical outcomes.[1,9,10] --- ## Clinical presentation AF ranges from completely asymptomatic to shock. Common symptoms: - palpitations; - dyspnea; - reduced exercise tolerance; - fatigue; - chest discomfort; - lightheadedness / presyncope; - anxiety-like awareness of irregular heartbeat; - worsening heart failure; - stroke/TIA as the first manifestation. #### Red flags - hypotension/shock; - ongoing ischemic chest pain; - acute pulmonary edema or severe hypoxemia; - syncope with very rapid or very slow rate; - altered mental status from poor perfusion; - pre-excited AF with very rapid, irregular, wide-complex rhythm; - focal neurologic deficit suggesting stroke; - severe bradycardia/pauses after AF termination; - suspected acute coronary syndrome, PE, myocarditis, or aortic catastrophe. --- ## History A focused but high-yield AF history should establish: ### Episode characteristics - exact or best-estimate onset time; - continuous vs intermittent symptoms; - prior episodes and spontaneous conversion; - prior cardioversion/ablation; - prior antiarrhythmic drugs and failures; - rate-control medication adherence. ### Thromboembolic history - prior ischemic stroke/TIA/systemic embolism; - anticoagulant name, dose, adherence, last dose; - missed DOAC doses; - warfarin INR history/time in therapeutic range; - prior bleeding; - LAAO history. ### Precipitants - fever/infection; - vomiting/diarrhea/dehydration; - alcohol binge; - stimulant use; - thyrotoxic symptoms; - recent surgery; - hypoxia/OSA; - chest pain/PE symptoms; - acute HF symptoms. ### Structural heart disease - MI/CAD; - heart failure; - valvular disease; - cardiomyopathy; - congenital heart disease; - prior echo/LVEF. ### Medication risks - QT-prolonging drugs; - digoxin; - AV nodal blockers; - CYP3A4/P-gp interacting drugs; - antiarrhythmics; - renal/hepatic impairment affecting DOAC exposure. --- ## Examination Assess: - heart rate and rhythm; - blood pressure and perfusion; - oxygen saturation and respiratory distress; - signs of congestion (JVP, edema, crackles); - murmurs suggesting valve disease; - thyrotoxicosis signs; - neurologic deficit; - evidence of infection/sepsis; - volume depletion; - pulse deficit. **Clinical pearl:** A radial pulse can underestimate ventricular rate during AF because some ventricular contractions generate insufficient stroke volume to produce a palpable peripheral pulse. Use ECG/monitoring when the rate matters. --- ## Diagnosis and initial investigations ### 12-lead ECG Confirm AF and look for: - ventricular rate; - QRS width; - ischemia; - prior infarction; - LVH; - bundle-branch block; - pre-excitation; - QT interval (important before many antiarrhythmics). ### Basic laboratory workup Tailor to context, commonly: - CBC; - electrolytes, including potassium and magnesium; - renal function; - liver tests when anticoagulant/antiarrhythmic choice requires; - TSH (especially new AF or thyrotoxic symptoms); - glucose/HbA1c and cardiovascular-risk assessment; - troponin when ACS/ischemia is clinically suspected rather than reflexively in every uncomplicated AF episode. ### Echocardiography A transthoracic echocardiogram usually assesses: - LVEF; - LA size; - valve disease; - LVH; - right-heart disease; - structural cardiomyopathy. TEE/TOE is used when left atrial/LAA thrombus exclusion will change cardioversion or procedural management. ### Ambulatory monitoring Useful for: - intermittent symptoms; - quantifying AF burden; - rate-control adequacy; - post-ablation surveillance; - correlating symptoms with rhythm; - detecting pauses/bradycardia. --- ## Differential diagnosis of an irregular rhythm | Rhythm / condition | Distinguishing features | |---|---| | **Atrial flutter with variable block** | Organized flutter waves, often atrial rate ~300/min; ventricular rhythm may be irregular | | **Multifocal atrial tachycardia (MAT)** | Irregular rhythm with ≥3 distinct P-wave morphologies and visible isoelectric baseline; often COPD/hypoxemia | | **Sinus rhythm with frequent PACs** | Underlying sinus P waves with premature atrial beats | | **Sinus arrhythmia** | P before each QRS; respiratory pattern, often younger patients | | **Frequent PVCs** | Premature wide complexes; underlying organized atrial rhythm | | **Pre-excited AF** | Very rapid irregular wide-complex tachycardia, variable QRS morphology; dangerous accessory-pathway conduction | --- ## Acute management algorithm ```text ECG-confirmed atrial fibrillation ↓ Is AF causing hemodynamic instability? (hypotension/shock, ischemia, pulmonary edema, critical hypoperfusion) ├─ YES → immediate synchronized electrical cardioversion │ + anticoagulation as soon as safely feasible │ + treat precipitating cause │ └─ NO ↓ Stable: assess - ventricular rate and symptoms - LVEF / HF status - pre-excitation? - AF duration / anticoagulation status - trigger (sepsis, hypoxia, thyroid, ACS, PE, alcohol, etc.) ↓ Pre-excited AF? ├─ YES → avoid AV-nodal blockers │ stable: IV procainamide or ibutilide / cardioversion │ unstable: electrical cardioversion └─ NO ↓ Need immediate rhythm restoration? ├─ NO → rate control + trigger treatment + stroke prevention └─ YES → cardioversion strategy based on duration and thrombus risk ↓ Long-term plan: AF-CARE comorbidities + anticoagulation + rate/rhythm strategy + reassessment ``` --- ## Hemodynamically unstable AF **STANDARD OF CARE:** If AF is causing acute or worsening hemodynamic instability, synchronized electrical cardioversion is the fastest and preferred treatment.[1,2] Examples: - shock/hypotension attributable to the tachyarrhythmia; - ongoing myocardial ischemia; - acute pulmonary edema; - severe low-output symptoms. Provide procedural sedation if feasible **without delaying life-saving cardioversion**. Confirm synchronization before the shock. Escalate energy according to device/local protocol if unsuccessful. Anticoagulation should be initiated as soon as safely possible around emergency cardioversion, but anticoagulation logistics must not postpone immediate resuscitative treatment.[1,2] --- ## Stable AF with rapid ventricular response: rate control ### First treat the patient, not just the monitor Before adding AV-nodal blockade, ask: - Is tachycardia compensatory for sepsis, hemorrhage, hypoxia, PE, or shock? - Is there decompensated HFrEF? - Is the QRS wide/irregular suggesting pre-excitation? - Is blood pressure adequate? Treating a compensatory tachycardia with aggressive rate-control drugs can worsen shock. ### Guideline-supported acute rate-control choices In **hemodynamically stable AF with RVR**, the 2023 ACC/AHA guideline recommends a beta blocker or nondihydropyridine calcium-channel blocker (diltiazem/verapamil) when **LVEF >40%**. Digoxin can be considered if those agents are ineffective or contraindicated; IV magnesium may be a useful adjunct. In critically ill patients or decompensated HF where standard AV-nodal blockers are unsuitable, IV amiodarone may be considered.[1] #### Common adult rate-control doses (2023 ACC/AHA table) | Drug | Acute IV regimen | Oral maintenance | Key cautions | |---|---|---|---| | **Metoprolol tartrate** | 2.5–5 mg IV over 2 min; up to 3 doses | 25–200 mg twice daily | Hypotension, bradycardia, bronchospasm; titrate in HF | | **Esmolol** | 500 mcg/kg bolus over 1 min, then 50–300 mcg/kg/min | — | Short half-life useful when rapid titration desired | | **Diltiazem** | 0.25 mg/kg IV over 2 min; may repeat 0.35 mg/kg; then 5–15 mg/h | ER 120–360 mg/day | **Avoid in HFrEF** / significant LV systolic dysfunction | | **Verapamil** | 5–10 mg IV over ≥2 min; may repeat; infusion up to 20 mg/h | ER 180–480 mg/day | **Avoid in HFrEF**, hypotension, AV block | | **Digoxin** | 0.25–0.5 mg IV, then 0.25 mg q6h; max 1.5 mg/24 h | 0.0625–0.25 mg/day | Renal clearance; slower onset; toxicity/interactions | | **Amiodarone** | 150–300 mg IV over 1 h, then 10–50 mg/h over 24 h | Usually 100–200 mg/day when used chronically | Can cardiovert → thromboembolic considerations; thyroid/lung/liver toxicity | Doses are guideline examples, not automatic prescriptions. Renal function, age, weight, BP, conduction disease, HF, and local protocols matter.[1] ### Rate target For many stable patients without severe HF, a **lenient resting rate <110 bpm** is a reasonable initial target if symptoms are controlled. RACE II found lenient control noninferior to stricter control in a selected population; however, patients with arrhythmia-induced cardiomyopathy, persistent symptoms, CRT pacing needs, or HF may require more stringent individualized control.[1] **Board trap:** “Heart rate 130” does not prove the AF is the primary disease process. In septic shock, the correct treatment may be source control and resuscitation rather than escalating diltiazem. --- ## Pre-excited AF (WPW): a critical exception Pre-excited AF can conduct extremely rapidly down an accessory pathway and degenerate into ventricular fibrillation. #### ECG clues - very fast irregular rhythm; - wide complexes; - variable QRS morphology; - very short RR intervals; - known WPW may or may not be documented previously. #### Management **Unstable:** immediate synchronized electrical cardioversion.[1] **Stable:** IV **procainamide or ibutilide** is recommended as a pharmacologic option, or proceed to cardioversion.[1] #### DO NOT give AV-nodal blockers The 2023 ACC/AHA guideline classifies the following as **harmful/contraindicated** in pre-excited AF because AV-node block may accelerate accessory-pathway conduction and precipitate VF:[1] - adenosine; - beta blockers; - diltiazem; - verapamil; - digoxin; - **amiodarone**. Definitive therapy is catheter ablation of the accessory pathway.[1] --- ## Rhythm control: who benefits? The old paradigm “rate control for most, rhythm control only for symptoms” has shifted. Rhythm control is considered when: - symptoms persist despite adequate rate control; - AF is recently diagnosed and patient has cardiovascular risk where early rhythm control may improve outcomes; - AF is causing or worsening cardiomyopathy/HF; - rate control is difficult; - the patient strongly prefers sinus rhythm; - maintaining sinus rhythm may improve exercise capacity or quality of life; - AF is paroxysmal and catheter ablation is an attractive first-line strategy. ### EAST-AFNET 4 changed the strategy In 2,789 patients with early AF (median 36 days since diagnosis) and cardiovascular conditions, early rhythm control reduced the composite of cardiovascular death, stroke, or hospitalization for worsening HF/ACS: **3.9 vs 5.0 events per 100 person-years; HR 0.79** over median 5.1 years.[8] **Clinical implication:** Rhythm control is not merely cosmetic symptom treatment in all patients; in selected recently diagnosed AF, starting rhythm control early can improve cardiovascular outcomes. --- ## Cardioversion ### Electrical vs pharmacologic Electrical cardioversion is: - mandatory in hemodynamic instability; - highly effective when rapid restoration is desired; - often chosen for persistent AF or failed drug conversion. Pharmacologic cardioversion may be appropriate in stable patients, depending on structural heart disease, QT interval, renal function, drug availability, and local protocol. ### Common pharmacologic options | Agent | Typical role | Major limitations | |---|---|---| | **Flecainide** | Conversion / pill-in-the-pocket in selected patients without structural heart disease | Avoid prior MI/significant structural disease/HFrEF; risk 1:1 flutter; first PITP dose monitored | | **Propafenone** | Similar to flecainide | Same structural-heart-disease caution; interactions | | **Ibutilide IV** | Rapid pharmacologic conversion, especially flutter | QT prolongation/TdP; avoid significant HFrEF | | **Amiodarone IV/oral** | Useful when structural heart disease/HFrEF limits options | Slower conversion; many extracardiac toxicities | | **Procainamide IV** | Alternative conversion agent; key role in stable pre-excited AF | Hypotension, QRS/QT widening; caution HFrEF | The 2023 ACC/AHA table lists ibutilide **1 mg IV over 10 min if ≥60 kg** (0.01 mg/kg if <60 kg), with a possible second equal dose; and procainamide **1 g IV over 30 min**, followed by 2 mg/min infusion for 1 hour in studied protocols.[1] Use local drug protocols and monitoring. --- ## Anticoagulation around cardioversion: important US–European difference ### 2023 ACC/AHA/ACCP/HRS (US) For **AF duration ≥48 hours**, patients undergoing elective cardioversion should have either:[1] - **≥3 weeks uninterrupted therapeutic anticoagulation**, or - imaging (usually TEE/TOE; delayed cardiac CT can be an alternative in selected centers) excluding intracardiac thrombus. Therapeutic anticoagulation should be established before cardioversion and continued **for at least 4 weeks afterward**.[1] The guideline also notes that thromboembolic risk in AF <48 hours is not homogeneous; risk rises with patient substrate and duration, so the “48-hour rule” should not be treated as absolute biologic safety.[1] ### 2024 ESC/EACTS (Europe) ESC 2024 deliberately tightened the early-cardioversion threshold to **24 hours**. If known AF duration is **>24 hours**, early cardioversion without either ≥3 weeks therapeutic anticoagulation or TOE/TEE exclusion of thrombus is not recommended.[2,3] Most patients receive **at least 4 weeks anticoagulation after cardioversion**. ESC allows an exception in very low-risk patients with definite AF onset <24 h and no thromboembolic risk factors, but long-term anticoagulation is otherwise determined by stroke risk, not by maintenance of sinus rhythm.[2,3] #### Practical lesson When caring for a patient around 24–48 hours of known AF duration, **know your jurisdiction and local protocol**. ESC 2024 is intentionally more conservative than the traditional US 48-hour threshold. --- ## Stroke prevention ### Stroke risk is separate from rhythm strategy A patient who appears to be in sinus rhythm after cardioversion or ablation may still require long-term anticoagulation. Both major guidelines base anticoagulation on **thromboembolic risk**, not on whether the most recent ECG shows AF.[1,2] ### CHA₂DS₂-VASc (US / widely used) | Risk factor | Points | |---|---:| | Congestive heart failure/LV dysfunction | 1 | | Hypertension | 1 | | Age ≥75 years | 2 | | Diabetes mellitus | 1 | | Prior stroke/TIA/systemic embolism | 2 | | Vascular disease (MI, PAD, aortic plaque) | 1 | | Age 65–74 years | 1 | | Sex category: female | 1 | The 2023 ACC/AHA guideline recommends anticoagulation for estimated annual thromboembolic risk **≥2%**, approximately equivalent to CHA₂DS₂-VASc **≥2 in men or ≥3 in women**, and considers anticoagulation reasonable at intermediate risk (~1–2%/year; about score 1 in men or 2 in women).[1] ### CHA₂DS₂-VA (ESC 2024) ESC 2024 removes the sex-category point:[2] - **0:** generally no OAC for AF alone; - **1:** OAC should be considered; - **≥2:** OAC recommended. The goal is to simplify risk assessment and avoid using sex as a stand-alone risk factor. ### Bleeding risk Use bleeding-risk assessment to **identify modifiable risk**, not to automatically deny anticoagulation. Address: - uncontrolled hypertension; - NSAIDs/antiplatelets where avoidable; - excessive alcohol; - anemia/bleeding source; - renal/hepatic dysfunction; - labile INR on warfarin; - fall-risk contributors; - drug interactions. ESC 2024 supports HAS-BLED to flag patients needing closer review; a high score is not itself an instruction to withhold OAC.[2] --- ## Oral anticoagulants ### DOACs vs warfarin **DOACs are preferred** in most eligible AF patients because pivotal trials and meta-analyses show at least comparable efficacy with less intracranial hemorrhage than warfarin overall.[1] #### Use warfarin/VKA instead when - mechanical prosthetic heart valve; - clinically significant/rheumatic mitral stenosis (moderate–severe); - certain severe renal/hepatic situations where a DOAC is unsuitable; - cost/access/adherence considerations favor VKA; - interacting drugs make DOAC exposure unreliable. Warfarin for AF is generally targeted to **INR 2.0–3.0** unless another indication requires a different target. ### Common US-labeled DOAC doses for nonvalvular AF | DOAC | Standard dose | Common renal/clinical adjustment | Key points | |---|---|---|---| | **Apixaban** | 5 mg twice daily | 2.5 mg BID if **at least 2**: age ≥80, weight ≤60 kg, serum creatinine ≥1.5 mg/dL | Strong CYP3A4/P-gp interactions matter | | **Rivaroxaban** | 20 mg once daily **with the biggest/evening meal** | 15 mg once daily when CrCl ≤50 mL/min in US labeling | Take with food; interaction/renal review | | **Dabigatran** | 150 mg twice daily if CrCl >30 | US: 75 mg BID at CrCl 15–30; interaction-specific modifications exist | ~80% renal elimination; dyspepsia/GI bleeding considerations | | **Edoxaban** | 60 mg once daily when CrCl >50 to ≤95 | 30 mg once daily with reduced renal function (and other criteria by label) | US AF labeling avoids CrCl >95 because of reduced efficacy signal | These are **US guideline/package-label examples**.[1] European and other national labels differ—e.g., dabigatran 110 mg BID is used in selected patients outside the US, and edoxaban reduction criteria include weight and P-gp inhibitors. Always use the local product label. #### Avoid inappropriate underdosing ESC 2024 explicitly advises against reducing a DOAC dose unless the patient meets the drug-specific criteria because underdosing can produce preventable thromboembolism.[2] --- ## Antiplatelet therapy is not a substitute for anticoagulation Aspirin alone, or aspirin plus clopidogrel, is **not recommended as an alternative to OAC** for AF stroke prevention in a patient who qualifies for anticoagulation and has no separate antiplatelet indication.[1,2] For patients with AF and stable coronary disease well beyond PCI/ACS, antithrombotic regimens should be simplified according to current CAD/PCI guidance to minimize bleeding; many patients ultimately require **OAC alone** rather than indefinite OAC plus aspirin.[1] --- ## Left atrial appendage occlusion (LAAO) The 2023 US guideline gives percutaneous LAAO a stronger role:[1] - **reasonable (Class 2a)** in patients with CHA₂DS₂-VASc ≥2 who have a contraindication to long-term OAC; - **may be reasonable (Class 2b)** as an alternative in moderate–high stroke risk with high major-bleeding risk on OAC, after shared decision-making. LAAO is not “risk-free anticoagulation avoidance.” It carries procedural risks and usually requires a defined post-procedure antithrombotic regimen. #### 2025–2026 emerging evidence Recent trials continue to refine whether LAA closure can substitute for DOACs in broader populations. Some 2026 data are encouraging, whereas other high-risk studies failed noninferiority. **Current guideline-based OAC remains the standard for eligible patients**; do not generalize conference-era/device-specific results beyond their populations.[14] --- ## Long-term rate control Long-term rate control is reasonable for: - permanent AF; - minimal symptoms; - rhythm-control failure or patient preference; - patients where procedural/drug rhythm control carries unfavorable risk. #### Common agents - beta blocker; - diltiazem/verapamil when LVEF is preserved (>40% per ESC/ACC guidance); - digoxin, especially when HF/hypotension limits alternatives or as add-on therapy; - AV-node ablation with pacing in selected refractory cases. #### HFrEF Avoid diltiazem/verapamil in significant LV systolic dysfunction because of negative inotropy. Beta blockers and/or digoxin are common rate-control choices depending on decompensation, BP, and clinical context.[1,2] --- ## Long-term rhythm control: antiarrhythmic drugs Drug choice is determined by structural heart disease, coronary disease, LVEF, renal function, QT, conduction system disease, and interaction profile. | Clinical setting | Reasonable options / concepts | Avoid / caution | |---|---|---| | **No prior MI or significant structural heart disease** | Flecainide, propafenone; dronedarone; dofetilide; sotalol in selected patients | Class Ic if structural disease develops | | **HFrEF (LVEF ≤40%)** | Amiodarone or dofetilide are established US options | Flecainide/propafenone; dronedarone in recent decompensated/advanced HF; sotalol often poorly suited | | **Prior MI / significant scar** | Amiodarone, dofetilide; specialist strategy | Flecainide/propafenone (harm/proarrhythmia) | | **Marked QT prolongation / low K/Mg** | Correct factors before QT-active drugs | Dofetilide, sotalol, ibutilide without careful monitoring | | **Severe renal dysfunction** | Agent-specific specialist dosing | Dofetilide/sotalol accumulation; digoxin accumulation | ### Important drug pearls #### Flecainide / propafenone Use only when significant structural heart disease/scar/prior MI is absent. An AV-nodal blocker is often paired to prevent 1:1 conduction if atrial flutter occurs. “Pill-in-the-pocket” therapy should be restricted to carefully selected patients after a monitored first dose confirms safety.[1] #### Amiodarone Effective across a wide range of structural heart disease but carries cumulative: - thyroid toxicity; - pulmonary toxicity; - hepatic toxicity; - corneal/skin effects; - bradycardia/QT effects; - numerous drug interactions. For long-term maintenance, the 2023 ACC/AHA guideline notes low-dose **100–200 mg/day** can be effective but should generally be reserved when safer options are ineffective/not preferred because of adverse effects.[1] #### Dofetilide Effective in HFrEF but requires renal dosing and QT monitoring. In US practice, initiation/reloading requires monitored hospitalization (typically at least 3 days) because of torsades risk.[1] #### Sotalol Requires QT, renal, potassium, and magnesium monitoring. It can cause torsades and bradycardia and is often initiated under monitored conditions, especially with risk factors.[1] #### Dronedarone Can be useful in selected patients without recent decompensated HF/severe LV dysfunction. It is **harmful in NYHA III/IV HF or recent decompensated HF** and should not be used for permanent AF as a strategy to improve outcomes.[1] --- ## Catheter ablation Pulmonary vein isolation (PVI) is the cornerstone of AF catheter ablation. ### When to consider ablation - symptomatic AF despite or intolerant of antiarrhythmic drugs; - selected symptomatic paroxysmal AF as **first-line rhythm control**; - symptomatic persistent AF after drug failure, and sometimes earlier by shared decision-making; - AF with HFrEF when arrhythmia contributes to cardiomyopathy or symptoms; - recurrent AF where durable sinus rhythm is a high priority. The 2024 EHRA/HRS/APHRS/LAHRS consensus expanded first-line ablation indications and recognizes improved safety and newer technologies including pulsed-field ablation.[10] ### Outcomes: what ablation does well Ablation is superior to antiarrhythmic drug therapy for reducing recurrent AF in many selected patients and often improves symptoms and quality of life. #### CABANA In 2,204 symptomatic AF patients, ablation did **not** significantly reduce the intention-to-treat primary composite of death, disabling stroke, serious bleeding, or cardiac arrest (**8.0% vs 9.2%; HR 0.86, P=.30**), but reduced AF recurrence (**49.9% vs 69.5%; HR 0.52**) and the secondary composite of death/CV hospitalization.[15] #### CASTLE-AF In selected patients with symptomatic AF and HFrEF (LVEF ≤35%) with implanted devices, catheter ablation reduced death/HF hospitalization versus medical therapy and improved LVEF; all-cause mortality was **13.4% vs 25.0% (HR 0.53)** in the original trial report.[9] **Interpretation:** Ablation is not simply a symptom procedure in all HF patients; selected HFrEF patients can gain prognostic benefit. --- ## Anticoagulation after ablation Do not stop OAC merely because ablation “worked.” ESC 2024 recommends OAC for **at least 2 months after AF ablation in all patients**, then long-term continuation according to thromboembolic risk rather than rhythm outcome.[2] The 2023 ACC/AHA approach similarly bases long-term OAC on stroke risk rather than perceived elimination of AF.[1] #### Emerging 2026 evidence OCEAN and ALONE-AF have renewed debate about stopping anticoagulation after apparently successful ablation in carefully monitored, selected patients. However, event rates were low and trial designs have limitations. As of September 2026, **guidelines have not been replaced**: elevated-risk patients should continue OAC according to guideline risk assessment.[16] --- ## Comorbidity and risk-factor management: disease-modifying AF treatment Risk-factor treatment reduces recurrence, improves procedural success, and addresses the same substrate driving stroke/HF. ### ESC 2024 high-yield targets - treat hypertension; - optimize HF therapy; - manage diabetes; - target **≥10% body-weight reduction** in overweight/obese AF patients as part of comprehensive management; - evaluate and manage obstructive sleep apnea where appropriate; - encourage tailored exercise; - reduce alcohol to **≤3 standard drinks (≤30 g alcohol) per week** to reduce recurrence; - stop smoking.[2] The 2026 AHA/ACC performance measures explicitly make secondary prevention—weight management, physical activity, smoking cessation, alcohol moderation, and BP control—a quality focus rather than an optional lifestyle footnote.[13] --- ## Special populations and scenarios ### AF + HFrEF Priorities: - determine whether AF is causing or worsening cardiomyopathy; - avoid nondihydropyridine calcium-channel blockers when LVEF is significantly reduced; - optimize guideline-directed HF therapy; - consider early rhythm control and catheter ablation; - maintain stroke prevention according to risk. The 2023 ACC/AHA guideline gives catheter ablation a strong role in appropriate AF + HFrEF patients, supported by CASTLE-AF and subsequent evidence.[1,9] ### Hyperthyroidism Treat the thyroid disease plus rate/rhythm consequences. Beta blockade is often useful if not contraindicated. Stroke prevention still follows thromboembolic risk; do not assume AF becomes harmless simply because hyperthyroidism is reversible. ### Postoperative / “trigger-induced” AF AF during surgery, sepsis, pneumonia, or another acute trigger has a meaningful recurrence risk. The 2023 ACC/AHA guideline recommends outpatient follow-up for thromboembolic risk assessment and AF surveillance after AF identified during acute illness or surgery.[1] In sepsis-related AF, the benefit of starting anticoagulation *during the critical illness* solely for stroke prevention is uncertain; reassess after stabilization.[1] ### Pregnancy Management requires cardiology–maternal-fetal medicine coordination. Avoid DOACs because safety is not established and they are generally not recommended. Rate/rhythm drug selection and cardioversion are pregnancy-specific; electrical cardioversion can be performed when clinically necessary. Anticoagulation choice depends on gestational timing and indication, usually using heparin-based strategies and/or carefully managed VKA in selected high-risk valve situations under specialist care. ### CKD - recalculate renal function periodically; - adjust DOACs according to label and actual renal function; - avoid “set-and-forget” dosing as kidney function changes; - warfarin or apixaban may be used in selected advanced CKD/dialysis patients under guideline/shared decision-making, but evidence is less robust than in preserved renal function.[1] ### Hypertrophic cardiomyopathy / cardiac amyloidosis Stroke risk can be high independent of ordinary scores. ESC recommends OAC in AF with HCM or cardiac amyloidosis regardless of CHA₂DS₂-VA.[2] ### Athletes Assess reversible triggers, atrial remodeling, stimulant/supplement exposure, and exercise volume. Rate-control drugs may impair performance. Rhythm-control/ablation strategies may be particularly attractive after individualized electrophysiology review. --- ## Device-detected subclinical AF / atrial high-rate episodes (AHRE) This is one of the fastest-changing areas in AF medicine. ### 2023 ACC/AHA approach For patients **without a prior clinical AF diagnosis**:[1] - device-detected AHRE **5 min–24 h** with CHA₂DS₂-VASc ≥3: OAC **may be reasonable** after shared decision-making that considers episode duration and individual stroke risk; - AHRE **<5 min** with no other indication: **do not anticoagulate** solely for that episode. ### ARTESiA 4,012 patients with subclinical AF were randomized to apixaban vs aspirin. Apixaban reduced stroke/systemic embolism from **1.24% to 0.78% per patient-year (HR 0.63)** but increased major bleeding from **0.94% to 1.71% per patient-year (HR 1.80)**.[11] ### NOAH-AFNET 6 2,536 patients with AHREs were randomized to edoxaban or placebo. Edoxaban did not significantly reduce cardiovascular death/stroke/systemic embolism (**HR 0.81; P=.15**) and increased the composite of death or major bleeding (**HR 1.31**); stroke rates were low (~1%/year).[12] #### Interpretation **EMERGING EVIDENCE:** AF burden matters. A 6-minute device episode is not biologically identical to persistent clinical AF. Anticoagulation decisions for device-detected AF require shared decision-making integrating duration, stroke risk, bleeding risk, and certainty that the recorded episode is true AF. --- ## Complications ### Thromboembolic - ischemic stroke; - TIA; - systemic arterial embolism; - cognitive decline/dementia association over time. ### Cardiac - tachycardia-induced cardiomyopathy; - HF decompensation; - myocardial ischemia from supply-demand mismatch; - bradycardia/pauses due to sinus-node disease or medication; - atrial functional mitral/tricuspid regurgitation; - AF progression from paroxysmal to persistent/permanent. ### Treatment-related - anticoagulant bleeding; - antiarrhythmic proarrhythmia; - amiodarone organ toxicity; - bradycardia/AV block from rate-control therapy; - ablation complications (tamponade, vascular injury, stroke, pulmonary vein stenosis, rare atrioesophageal fistula, phrenic injury depending on technique). --- ## Monitoring and follow-up AF is dynamic; reassess periodically. ### At routine follow-up - symptoms and functional status; - rhythm/AF burden where relevant; - resting/exertional rate; - BP; - weight/obesity intervention; - alcohol/smoking/exercise; - sleep apnea management; - HF status; - anticoagulant adherence and dose appropriateness; - renal/hepatic function; - bleeding/anemia; - drug interactions; - antiarrhythmic ECG/toxicity monitoring; - changing CHA₂DS₂-VASc or CHA₂DS₂-VA risk. The **2026 AHA/ACC performance measures** specifically emphasize documenting a validated stroke/systemic-embolism risk assessment **annually** and prescribing appropriate anticoagulation.[13] --- ## Anticipating deterioration | Warning sign | Concern | Immediate action | |---|---|---| | Hypotension, pulmonary edema, ischemia with AF | AF causing instability | Synchronized cardioversion | | Very rapid irregular wide-complex rhythm | Pre-excited AF | Avoid AV-nodal blockers; cardioversion if unstable, procainamide/ibutilide if stable | | New focal neurologic deficit | AF-related stroke | Activate acute stroke pathway immediately; anticoagulation timing becomes stroke-specific | | Rising rate despite escalating blockers + sepsis/hypoxia | Compensatory tachycardia / untreated trigger | Treat underlying shock/trigger; avoid reflex drug escalation | | New LVEF reduction with high AF burden | Arrhythmia-induced cardiomyopathy | Early rhythm-control/EP evaluation | | Syncope or pauses after AF termination | Tachy-brady syndrome | Monitor; review AV nodal drugs; pacing evaluation if clinically indicated | | Bleeding on OAC | Anticoagulant complication | Stabilize, identify site, drug-specific reversal strategy if life-threatening | | Missed DOAC doses before planned cardioversion | Inadequate thrombus protection | Re-establish required anticoagulation period or use TEE/TOE-guided strategy | --- ## Common pitfalls | Pitfall | Why it is dangerous | Better approach | |---|---|---| | Treating every AF rate >120 as the primary problem | Tachycardia may be compensatory | Search for sepsis, hypovolemia, PE, hypoxia, ACS first | | Giving diltiazem/verapamil in decompensated HFrEF | Negative inotropy can worsen instability | Beta blocker only when appropriate, digoxin, amiodarone/other specialist strategy | | Giving AV-nodal blockers in pre-excited AF | Can accelerate accessory-pathway conduction → VF | Procainamide/ibutilide or cardioversion | | Using aspirin instead of anticoagulation | Inadequate AF stroke prevention | Use guideline-directed OAC when indicated | | Underdosing a DOAC “because the patient is old” | Increases preventable stroke if reduction criteria not met | Apply drug-specific label criteria | | Stopping OAC because sinus rhythm was restored | Stroke risk persists despite rhythm success | Anticoagulate by thromboembolic risk | | Assuming AF <48 h is always safe to cardiovert without anticoagulation | Risk varies by patient; ESC now uses 24 h | Follow local guideline and thromboembolic-risk strategy | | Using a bleeding score to deny OAC automatically | Withholds proven stroke prevention | Fix modifiable bleeding risks and increase follow-up | | Leaving obesity/OSA/alcohol untreated | Promotes recurrence and ablation/drug failure | Treat AF substrate with risk-factor management | | Calling post-sepsis AF “transient” and never following up | Recurrence and stroke risk can persist | Arrange surveillance and reassess OAC risk | --- ## STANDARD OF CARE vs EMERGING EVIDENCE vs EXPERIMENTAL ### STANDARD OF CARE - ECG confirmation of AF.[1,2] - Immediate synchronized cardioversion when AF causes hemodynamic instability.[1,2] - Rate control with beta blocker or diltiazem/verapamil in stable patients when LV function permits; digoxin/other agents according to context.[1] - No AV-nodal blockers in pre-excited AF.[1] - Stroke-risk assessment and guideline-directed OAC.[1,2] - DOACs preferred over warfarin except mechanical valves/significant mitral stenosis.[1,2] - Anticoagulation determined by thromboembolic risk, not apparent rhythm success.[1,2] - Risk-factor treatment (weight, BP, HF, diabetes, OSA, alcohol, exercise, smoking).[2,13] - Catheter ablation for appropriate symptomatic patients and selected AF + HFrEF populations.[1,2,10] ### EMERGING / RAPIDLY EVOLVING - Anticoagulation thresholds for **device-detected** subclinical AF after ARTESiA and NOAH-AFNET 6.[11,12] - Selective discontinuation of OAC after apparently successful ablation in carefully chosen lower-risk patients (OCEAN/ALONE-AF era); not yet a replacement for guideline risk-based anticoagulation.[16] - Pulsed-field ablation (PFA) as an increasingly used energy source with evolving comparative long-term data.[10] - Broader LAAO indications vs contemporary DOAC therapy.[14] - Wearable-derived AF burden as a risk modifier rather than binary diagnosis alone. ### EXPERIMENTAL / NOT ROUTINE - Anticoagulating every brief wearable/device-detected episode regardless of duration/risk. - Stopping anticoagulation solely because a smartwatch shows no AF after ablation. - Using AF-burden thresholds without validated clinical context to replace established stroke-risk assessment. - Novel mapping, autonomic modulation, or adjunctive ablation targets outside accepted protocols/trials. --- ## Guideline conflicts and jurisdiction differences ### 1. Stroke score - **US 2023:** validated annual risk estimate; CHA₂DS₂-VASc remains a common operational tool; female sex functions as a risk modifier in the score.[1] - **ESC 2024:** **CHA₂DS₂-VA**, removing sex category; consider OAC at 1, recommend at ≥2.[2] ### 2. Cardioversion timing - **US 2023:** ≥48 h AF → 3 weeks therapeutic anticoagulation or imaging before elective cardioversion; continue ≥4 weeks afterward.[1] - **ESC 2024:** >24 h known AF duration → do not perform early cardioversion without 3 weeks anticoagulation or TOE exclusion; most receive ≥4 weeks afterward.[2,3] ### 3. DOAC dosing Renal thresholds and approved lower doses differ by FDA, EMA, MHRA, and national labels. **Never transplant a US dose table into another jurisdiction without checking the local label.** --- ## Landmark and practice-shaping evidence ### EAST-AFNET 4 — early rhythm control (2020) - 2,789 patients with early AF and cardiovascular conditions. - Median time from AF diagnosis: 36 days. - Primary outcome: CV death, stroke, hospitalization for HF or ACS. - **3.9 vs 5.0 events/100 person-years; HR 0.79; P=.005** for early rhythm control vs usual care.[8] **Takeaway:** Selected early AF deserves proactive rhythm-control discussion even when symptoms are modest. ### CASTLE-AF — ablation in HFrEF (2018) Selected symptomatic AF patients with LVEF ≤35% and implanted devices had lower death/HF hospitalization with catheter ablation; all-cause mortality was **13.4% vs 25.0%; HR 0.53**.[9] **Takeaway:** In appropriate HFrEF, ablation can be prognostic therapy, not merely symptom therapy. ### CABANA — ablation vs drug strategy (2019) Ablation did not significantly reduce the primary intention-to-treat hard-event composite (**8.0% vs 9.2%, HR 0.86**) but substantially reduced AF recurrence and CV hospitalization-related secondary outcomes.[15] **Takeaway:** Ablation reliably improves rhythm control; interpretation of hard outcomes is influenced by crossover and patient selection. ### ARTESiA — device-detected AF (2024) Apixaban reduced stroke/systemic embolism (**0.78% vs 1.24%/year; HR 0.63**) but increased major bleeding (**1.71% vs 0.94%/year; HR 1.80**).[11] ### NOAH-AFNET 6 — AHRE (2023) Edoxaban did not significantly reduce the primary efficacy composite (**HR 0.81; P=.15**) and increased death/major-bleeding composite (**HR 1.31**).[12] **Takeaway:** Subclinical AF anticoagulation requires individualized net-benefit analysis. --- ## Exam-focused review ### USMLE Step 1 Know: - chaotic atrial depolarization → no organized P waves; - variable AV conduction → irregularly irregular ventricular rhythm; - loss of atrial kick is especially important in diastolic dysfunction; - LAA stasis → embolic stroke; - pulmonary veins are common AF triggers; - chronic AF causes electrical/structural remodeling. ### USMLE Step 2 CK Prioritize: - unstable AF → synchronized cardioversion; - stable RVR → rate control *after* assessing trigger and EF; - pre-excited AF → **no AV-nodal blockers**; - anticoagulation by stroke risk; - cardioversion anticoagulation based on duration/risk; - thyroid/electrolyte/structural evaluation in new AF. ### Step 3 / Resident Focus on: - anticoagulant dose/renal interactions; - distinguishing compensatory tachycardia from primary RVR; - when early rhythm control is prognostic; - post-ablation anticoagulation; - HFrEF-specific drug choices; - peri-cardioversion anticoagulation. ### MRCP / ABIM / Boards High-yield traps: - female sex alone does not mandate OAC; ESC removed sex from its score. - aspirin is not a substitute for OAC. - normal sinus rhythm after ablation does not automatically permit stopping OAC. - diltiazem/verapamil are inappropriate in significant HFrEF. - amiodarone is **also** an AV-nodal-blocking danger in pre-excited AF according to the 2023 US guideline. - device-detected AF has a different evidence base from clinical AF. - ESC 2024 uses a 24-hour early-cardioversion threshold; US 2023 retains the ≥48-hour Class I trigger for mandatory 3-week anticoagulation/imaging. --- ## Original MCQs ### Question 1 A 68-year-old man with AF presents with BP 72/40 mmHg, acute pulmonary edema, and a ventricular rate of 170/min. What is the next best step? A. Oral metoprolol B. IV digoxin and reassess in 6 hours C. Synchronized electrical cardioversion D. Start apixaban and wait 3 weeks E. TEE before any intervention **Answer: C.** AF is causing hemodynamic instability. Immediate synchronized cardioversion takes priority; anticoagulation is addressed as soon as safely feasible.[1,2] --- ### Question 2 A 28-year-old with known WPW presents with a very rapid irregular wide-complex tachycardia and stable blood pressure. Which is the most appropriate pharmacologic option? A. Adenosine B. Diltiazem C. Digoxin D. IV procainamide E. IV amiodarone **Answer: D.** Stable pre-excited AF can be treated with IV procainamide or ibutilide. AV-nodal blockers—including amiodarone in this setting—are contraindicated because they can precipitate VF.[1] --- ### Question 3 A 78-year-old woman with hypertension, diabetes, and paroxysmal AF is in sinus rhythm after successful ablation. She asks to stop anticoagulation because her smartwatch has shown no AF for 9 months. Which is most accurate? A. Anticoagulation is unnecessary if AF is not currently visible B. Ablation eliminates stroke risk completely C. Long-term anticoagulation should be based on thromboembolic risk, not perceived rhythm success D. Aspirin is equivalent to a DOAC after ablation E. Anticoagulation is required for only 24 hours after ablation **Answer: C.** Current ACC and ESC guidelines base long-term OAC on stroke risk. ESC requires OAC for at least 2 months after ablation in all patients, then continued according to risk.[1,2] --- ### Question 4 A patient with stable AF with RVR has an LVEF of 25% and acute decompensated heart failure. Which rate-control drug is least appropriate? A. Digoxin B. Carefully selected beta-blocker strategy after stabilization C. Diltiazem D. IV amiodarone in selected critically ill patients E. Specialist rhythm-control evaluation **Answer: C.** Diltiazem/verapamil should be avoided in significant HFrEF because of negative inotropy.[1,2] --- ### Question 5 A hemodynamically stable patient in Europe has definite AF onset 30 hours ago, has not been anticoagulated, and is being considered for elective cardioversion. According to ESC 2024, what is the safest guideline-consistent approach? A. Cardioversion without anticoagulation because AF is <48 h B. Proceed only after ≥3 weeks therapeutic anticoagulation or TOE/TEE exclusion of thrombus C. Aspirin for one dose before cardioversion D. Cardioversion and no postprocedure anticoagulation in all cases E. Anticoagulation is never needed if CHA₂DS₂-VA is 0 **Answer: B.** ESC 2024 reduced the un-anticoagulated early-cardioversion threshold from 48 to 24 hours.[2,3] --- ### Question 6 A pacemaker detects recurrent 1-hour AHRE episodes in a 77-year-old with hypertension and prior TIA, but no clinical AF on surface ECG. Which statement best reflects current evidence? A. All AHREs require anticoagulation regardless of duration/risk B. AHREs never carry stroke risk C. Anticoagulation should be individualized because ARTESiA showed fewer embolic events but more major bleeding, while NOAH-AFNET 6 showed no significant primary efficacy benefit and more safety events D. Aspirin is proven superior to apixaban E. The device should be ignored **Answer: C.** Device-detected AF/AHRE requires confirmation and net-benefit assessment rather than automatic treatment.[11,12] --- ### Question 7 A 64-year-old with recently diagnosed AF, hypertension, diabetes, and mild symptoms asks whether rhythm control is only for symptom relief. Which trial most directly changed this concept? A. RACE II B. EAST-AFNET 4 C. RE-LY D. ROCKET-AF E. AFFIRM only **Answer: B.** EAST-AFNET 4 showed early rhythm control reduced a composite of CV death, stroke, and HF/ACS hospitalization in selected patients with early AF and cardiovascular conditions.[8] --- ## Acute management checklist ### Recognition - [ ] Confirm AF on ECG. - [ ] Determine hemodynamic stability. - [ ] Look for pre-excitation / wide irregular tachycardia. - [ ] Estimate episode duration. - [ ] Identify anticoagulant use/adherence and last dose. ### Unstable - [ ] Synchronized electrical cardioversion. - [ ] Resuscitation/oxygenation as needed. - [ ] Anticoagulate as soon as clinically safe. - [ ] Treat precipitant (ACS, sepsis, PE, hypoxia, etc.). ### Stable RVR - [ ] Treat trigger first/alongside rate control. - [ ] Check LVEF/HF status before diltiazem/verapamil. - [ ] Beta blocker or nondihydropyridine CCB if appropriate. - [ ] Consider digoxin / magnesium / amiodarone in selected contexts. - [ ] Reassess BP, symptoms, rate, perfusion. ### Cardioversion planning - [ ] Verify AF duration and jurisdictional threshold. - [ ] US: ≥48 h → ≥3 wk OAC or imaging before elective cardioversion. - [ ] ESC: >24 h → ≥3 wk OAC or TOE before early cardioversion. - [ ] Continue OAC ≥4 wk after cardioversion in most patients/according to guideline. - [ ] Decide long-term OAC by stroke risk, not sinus rhythm. ### Long-term AF-CARE - [ ] **C:** BP, weight, HF, diabetes, OSA, alcohol, smoking, exercise. - [ ] **A:** annual stroke-risk reassessment; correct DOAC dose/adherence. - [ ] **R:** rate vs early rhythm control; consider ablation. - [ ] **E:** reassess symptoms, AF burden, renal function, bleeding, HF, evolving risks. --- ## References 1. **Joglar JA, Chung MK, Armbruster AL, et al.** 2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation. *Circulation.* 2024;149:e1-e156 / *J Am Coll Cardiol.* 2024;83:109-279. doi: **10.1016/j.jacc.2023.08.017**. Official ACC guideline: https://www.acc.org/Guidelines/Guidelines/2023/11/30/12/05/Atrial-Fibrillation-2023-Guideline 2. **Van Gelder IC, Rienstra M, Bunting KV, et al.; ESC Scientific Document Group.** 2024 ESC Guidelines for the management of atrial fibrillation developed in collaboration with EACTS. *Eur Heart J.* 2024;45:3314-3414. doi: **10.1093/eurheartj/ehae176**. https://www.escardio.org/guidelines/clinical-practice-guidelines/all-esc-practice-guidelines/atrial-fibrillation/ 3. **Kotecha D, et al.** Spotlight on the 2024 ESC/EACTS management of atrial fibrillation guidelines: 10 novel key aspects. *Europace.* 2025. PMID: **39716733**. 4. **Hindricks G, Potpara T, Dagres N, et al.** 2020 ESC Guidelines for the diagnosis and management of atrial fibrillation. *Eur Heart J.* 2021;42:373-498. doi:10.1093/eurheartj/ehaa612. (Historical comparator for changed recommendations.) 5. **Kirchhof P, Benussi S, Kotecha D, et al.** 2016 ESC Guidelines for the management of atrial fibrillation. *Eur Heart J.* 2016;37:2893-2962. doi:10.1093/eurheartj/ehw210. (Historical framework.) 6. **Van Gelder IC, Groenveld HF, Crijns HJGM, et al.; RACE II Investigators.** Lenient versus strict rate control in patients with atrial fibrillation. *N Engl J Med.* 2010;362:1363-1373. doi: **10.1056/NEJMoa1001337**. 7. **Al-Khatib SM, et al.** Contemporary evidence for pharmacological rate and rhythm control is incorporated in the 2023 ACC/AHA/ACCP/HRS guideline; use the guideline drug tables and local labeling for prescribing.[1] 8. **Kirchhof P, Camm AJ, Goette A, et al.; EAST-AFNET 4 Trial Investigators.** Early Rhythm-Control Therapy in Patients with Atrial Fibrillation. *N Engl J Med.* 2020;383:1305-1316. doi: **10.1056/NEJMoa2019422**. 9. **Marrouche NF, Brachmann J, Andresen D, et al.; CASTLE-AF Investigators.** Catheter Ablation for Atrial Fibrillation with Heart Failure. *N Engl J Med.* 2018;378:417-427. doi: **10.1056/NEJMoa1707855**. 10. **Tzeis S, et al.** 2024 EHRA/HRS/APHRS/LAHRS Expert Consensus Statement on Catheter and Surgical Ablation of Atrial Fibrillation. Endorsed by HRS, EHRA, APHRS, LAHRS. https://www.hrsonline.org/resource/2024-ehra-hrs-aphrs-lahrs-expert-consensus-statement-on-catheter-and-surgical-ablation-of-atrial-fibrillation/ 11. **Healey JS, Lopes RD, Granger CB, et al.; ARTESiA Investigators.** Apixaban for Stroke Prevention in Subclinical Atrial Fibrillation. *N Engl J Med.* 2024;390:107-117. doi: **10.1056/NEJMoa2310234**. PMID: **37952132**. 12. **Kirchhof P, Toennis T, Goette A, et al.; NOAH-AFNET 6 Investigators.** Anticoagulation with Edoxaban in Patients with Atrial High-Rate Episodes. *N Engl J Med.* 2023;389:1167-1179. doi: **10.1056/NEJMoa2303062**. 13. **Benjamin EJ, Marcus GM, Hess PL, et al.** 2026 AHA/ACC Clinical Performance and Quality Measures for Patients With Atrial Fibrillation. Published online August 17, 2026. *Circ Cardiovasc Qual Outcomes.* doi: **10.1161/HCQ.0000000000000149**; parallel JACC publication doi: **10.1016/j.jacc.2026.05.032**. https://professional.heart.org/en/science-news/2026-clinical-performance-and-quality-measures-for-patients-with-atrial-fibrillation 14. **ACC 2025–2026 LAAO trial reporting.** Contemporary LAA-closure evidence remains heterogeneous; current anticoagulation recommendations should not be displaced by individual new device trials without guideline integration. ACC Clinical Trials / Scientific Sessions 2025–2026. 15. **Packer DL, Mark DB, Robb RA, et al.; CABANA Investigators.** Effect of Catheter Ablation vs Antiarrhythmic Drug Therapy on Mortality, Stroke, Bleeding, and Cardiac Arrest Among Patients With Atrial Fibrillation. *JAMA.* 2019;321:1261-1274. doi: **10.1001/jama.2019.0693**. PMID: **30874766**. 16. **American College of Cardiology.** Discontinuation of Anticoagulation Following Catheter Ablation of AF: Updates With OCEAN Trial. July 1, 2026. Current guidelines still base long-term OAC on thromboembolic risk. https://www.acc.org/Latest-in-Cardiology/Articles/2026/06/29/15/28/Discontinuation-of-Anticoagulation --- ### NEXT-TOPIC LEDGER **Completed today:** Atrial Fibrillation **Do not repeat normalized title:** `atrial-fibrillation` **Suggested future linked topics:** Atrial flutter; Supraventricular tachycardia; Anticoagulation in AF; Cardioversion; Catheter ablation for AF; Bradyarrhythmias and tachy-brady syndrome; Wolff-Parkinson-White syndrome; Heart failure with atrial fibrillation1d:T84e6,## One-minute summary **Diabetic ketoacidosis (DKA)** is an acute metabolic emergency caused by insufficient effective insulin activity together with excess counterregulatory hormones, producing **ketogenesis, metabolic acidosis, osmotic diuresis, dehydration, and total-body electrolyte depletion**. The 2024 international consensus report endorsed by the ADA, EASD, AACE, JBDS, and Diabetes Technology Society modernized the adult diagnostic framework: DKA requires **(1) diabetes or glucose ≥200 mg/dL (11.1 mmol/L), (2) significant ketosis—preferably β-hydroxybutyrate ≥3.0 mmol/L, and (3) metabolic acidosis with pH <7.3 and/or bicarbonate <18 mmol/L**.[1,2] Management is simultaneous rather than sequential: **restore circulating volume, administer insulin, replace potassium and other electrolytes appropriately, add dextrose before ketoacidosis has resolved, identify the precipitant, and monitor closely until ketonemia and acidosis resolve**.[1] Quantitative **β-hydroxybutyrate** is preferred over urine ketones for diagnosis and monitoring because nitroprusside urine testing does not measure β-hydroxybutyrate and may paradoxically appear “worse” as DKA improves.[1,3] A crucial modern concept is **euglycemic DKA**, particularly with SGLT2 inhibitors, pregnancy, prolonged fasting, low-carbohydrate intake, and partial insulin treatment. A near-normal glucose does **not** exclude DKA if ketosis and acidosis are present.[1,4] ### Immediate priorities 1. Confirm DKA and assess severity. 2. Search for shock, infection, ischemia, missed insulin, pump failure, pregnancy, drugs/toxins, and SGLT2 inhibitor exposure. 3. Begin isotonic saline or balanced crystalloid; balanced solutions are increasingly favored when available. 4. Check potassium **before and during insulin therapy**. 5. Start insulin when potassium is safe; severe DKA generally uses IV insulin **0.1 units/kg/hour**.[1,2] 6. Add **5–10% dextrose once glucose falls below 250 mg/dL** so insulin can continue until ketoacidosis resolves.[2] 7. Reassess frequently; do not stop insulin merely because glucose has normalized. --- ## Definition and diagnostic criteria DKA is a syndrome of **diabetes/hyperglycemia, ketonemia, and metabolic acidosis** produced by absolute or relative insulin deficiency. In adults, all three diagnostic domains should be present.[1] | Domain | Current adult criterion | Practical interpretation | |---|---|---| | **D — diabetes/hyperglycemia** | Glucose **≥200 mg/dL (11.1 mmol/L)** **or** established diabetes | The lower glucose threshold recognizes euglycemic/near-euglycemic presentations | | **K — ketosis** | β-hydroxybutyrate **≥3.0 mmol/L** preferred; urine ketones ≥2+ if quantitative testing unavailable | β-hydroxybutyrate is the dominant ketone in DKA and best tracks recovery | | **A — acidosis** | Venous/arterial pH **<7.3** and/or bicarbonate **<18 mmol/L** | Mixed acid-base disorders can partially mask acidemia | The **anion gap is still clinically useful**, especially where β-hydroxybutyrate is unavailable, but it was removed from the primary 2024 diagnostic/severity criteria because vomiting, volume contraction, chloride-rich fluids, and other mixed disorders can alter the relationship between ketone burden and bicarbonate/anion gap.[1,3] ### Euglycemic DKA Euglycemic DKA describes ketoacidosis with glucose that is not markedly elevated. Important triggers include: - SGLT2 inhibitors - pregnancy - prolonged fasting or starvation physiology in a person with diabetes - vomiting and reduced carbohydrate intake - partial insulin treatment before presentation - alcohol use - acute illness with reduced intake **Board pearl:** A patient taking an SGLT2 inhibitor with nausea, tachypnea, abdominal pain, high anion gap, and β-hydroxybutyrate elevation may have DKA even with glucose 120–200 mg/dL. --- ## Epidemiology and outcomes Hyperglycemic crises are increasingly common. The 2024 consensus report notes a marked rise in adult DKA admissions over the preceding decade, particularly in adults younger than 45 years.[1] Most DKA still occurs in type 1 diabetes, but DKA also occurs in type 2 diabetes, ketosis-prone diabetes, pancreatic diabetes, and other insulin-deficient states. Recurrent DKA is common and often signals a preventable systems problem such as insulin access, diabetes distress, psychiatric disease, substance use, inadequate sick-day education, or device failure.[1] With timely modern care, **adult DKA mortality is usually <1%**, but risk rises with advanced age, severe comorbidity, sepsis, myocardial infarction, renal failure, profound acidosis, mixed DKA/HHS, and delayed treatment.[1] --- ## Etiology and precipitants | Precipitant | Clues | Immediate implication | |---|---|---| | **Insulin omission/interruption** | Missed doses, affordability issues, injection problems, pump interruption | Restore basal insulin strategy and address access/education before discharge | | **Infection** | Fever may be absent; UTI and pneumonia are common | Cultures/imaging as indicated; antibiotics only when infection is suspected/confirmed | | **New diabetes** | Weight loss, polyuria, polydipsia | Determine phenotype later; acute stabilization comes first | | **SGLT2 inhibitor** | Disproportionate ketosis with modest glucose | Stop drug; treat as DKA; consider euglycemic DKA | | **Acute coronary syndrome / stroke** | Chest pain, ECG/troponin changes, focal deficits | DKA may be precipitant or consequence; manage both emergencies | | **Pancreatitis** | Epigastric pain, elevated lipase; note DKA itself may mildly raise lipase | Diagnose pancreatitis clinically/imaging when appropriate, not by lipase alone | | **Pregnancy** | Lower glucose threshold, rapid ketosis | Obstetric/endocrine involvement; fetal status after maternal stabilization | | **Drugs** | Glucocorticoids, sympathomimetics, atypical antipsychotics, cocaine | Treat trigger; adjust diabetes plan | | **Pump/infusion-set failure** | Rapid deterioration in pump users because no long-acting insulin depot | Inspect device, tubing, site; give insulin by reliable route | --- ## Pathophysiology ### 1. Insulin deficiency and counterregulatory excess Reduced effective insulin plus increased glucagon, catecholamines, cortisol, and growth hormone causes: - increased hepatic gluconeogenesis and glycogenolysis → hyperglycemia - reduced peripheral glucose utilization - increased lipolysis → free fatty acids - hepatic conversion of free fatty acids to ketone bodies, especially **β-hydroxybutyrate** - accumulation of ketoacids → high-anion-gap metabolic acidosis ### 2. Osmotic diuresis and dehydration Glucosuria and ketonuria cause urinary water and electrolyte losses. Patients can have large deficits of: - water - sodium - potassium - phosphate - magnesium The serum potassium may initially be normal or high because insulin deficiency, hyperosmolality, and acidosis shift potassium extracellularly, even though **total-body potassium is depleted**. ### 3. Acid-base complexity Classic DKA causes high-anion-gap metabolic acidosis with respiratory compensation (Kussmaul breathing). Common concurrent disorders include: - metabolic alkalosis from vomiting - hyperchloremic metabolic acidosis during treatment, especially with large saline volumes - lactic acidosis from hypoperfusion - respiratory alkalosis from sepsis/pregnancy - respiratory acidosis if fatigue or CNS depression develops **Clinical implication:** A pH that is only mildly low—or even normal—does not exclude clinically important ketoacidosis when mixed disorders coexist.[3] --- ## Clinical presentation ### Symptoms - polyuria, polydipsia, thirst - weight loss - nausea and vomiting - abdominal pain - weakness/fatigue - dyspnea - confusion or reduced consciousness in severe disease ### Examination - tachycardia - dehydration: dry mucosa, poor skin turgor, low JVP - hypotension or orthostasis - tachypnea / **Kussmaul respirations** - acetone-like breath odor (not reliably present) - abdominal tenderness without peritonitis - altered mental status in severe DKA, mixed DKA/HHS, sepsis, or another CNS process ### Red flags - shock or persistent hypotension - hypoxemia - severe hypokalemia - pH <7.0 - β-hydroxybutyrate >6 mmol/L - coma/stupor - pregnancy - dialysis or severe renal failure - acute MI/stroke/sepsis - suspected cerebral edema - mixed DKA/HHS --- ## Initial assessment: what to do in the first 15–30 minutes | Component | Assessment | Interpretation | Immediate action | Anticipate deterioration | |---|---|---|---|---| | **Airway/mental status** | Ability to protect airway, GCS/AVPU | Marked depression suggests severe DKA, hyperosmolality, sepsis, stroke, intoxication | Airway support if required; avoid routine intubation solely for low pH | Loss of respiratory compensation after sedation/intubation can abruptly worsen acidemia | | **Breathing** | RR, SpO₂, work, chest exam | Kussmaul breathing is compensatory | Oxygen only if indicated; treat pulmonary precipitant | Fatigue or rising CO₂ is ominous | | **Circulation** | BP, pulse, capillary refill, JVP, urine output | Shock may be hypovolemic, septic, cardiogenic, or mixed | IV access, crystalloid, ECG, cause-specific shock care | Older/renal/cardiac patients are vulnerable to overload | | **Disability** | Glucose, pupils, neurologic exam | Hypoglycemia is not typical before therapy; focal deficits require separate evaluation | Bedside glucose immediately; CT/neurology if indicated after stabilization | Cerebral edema is rare in adults but serious | | **Exposure/cause** | Temperature, infection source, injection/pump sites, pregnancy possibility | Identify precipitant | Cultures/imaging/troponin/pregnancy test when indicated | DKA may coexist with sepsis, MI, pancreatitis | --- ## Diagnostic evaluation ### Essential tests - bedside and laboratory plasma glucose - **quantitative β-hydroxybutyrate** when available - venous blood gas (usually sufficient for pH monitoring) - sodium, potassium, chloride, bicarbonate - urea/BUN, creatinine - magnesium and phosphate - CBC - ECG - urinalysis - pregnancy test when relevant ### Directed tests for precipitant - blood/urine cultures if infection suspected - chest radiograph for respiratory symptoms or suspected pneumonia - troponin/serial ECG if ACS possible - lipase if pancreatitis is clinically suspected - toxicology testing only when clinically indicated - device/pump interrogation where relevant ### Useful calculations **Anion gap:** `Na − (Cl + HCO3)` Albumin-correct if necessary. Use as contextual information, especially when β-hydroxybutyrate is unavailable. **Effective osmolality (mOsm/kg):** `2 × Na (mmol/L) + glucose (mg/dL)/18` A markedly elevated osmolality or HHS-level hyperglycemia suggests a mixed DKA/HHS picture, which carries higher risk. --- ## Severity and level of care The 2024 consensus uses β-hydroxybutyrate, pH/bicarbonate, and mental status to guide severity and location of care.[1,2] | Severity | β-hydroxybutyrate | pH / bicarbonate | Mental status | Typical location | |---|---|---|---|---| | **Mild** | 3–6 mmol/L | pH >7.25; HCO3 ≥15 mmol/L | Alert | Observation/ward if adequate monitoring | | **Moderate** | 3–6 mmol/L | pH 7.0–7.25; HCO3 10 to <15 | Alert/drowsy | Step-down/intermediate care often appropriate | | **Severe** | >6 mmol/L | pH <7.0; HCO3 <10 | Stupor/coma possible | ICU/high-dependency care | Clinical judgment overrides classification. Severe comorbidity, shock, pregnancy, dialysis, HHS overlap, or need for organ support warrants higher-acuity care. --- ## Management ### STANDARD OF CARE — core treatment bundle #### 1. Fluids For adults **without cardiac or renal compromise**, the contemporary consensus recommends **isotonic saline or balanced crystalloid at approximately 500–1,000 mL/hour for the first 2–4 hours**, followed by individualized replacement based on hemodynamics, fluid balance, sodium, urine output, and comorbidity.[2] Balanced crystalloids are increasingly preferred where available because randomized and meta-analytic data suggest less hyperchloremic acidosis and potentially faster DKA resolution compared with saline.[1,2,5,6] ##### Practical fluid approach | Situation | Approach | |---|---| | Shock/severe hypovolemia | Rapid isotonic crystalloid with frequent reassessment; simultaneously look for sepsis/hemorrhage/cardiogenic causes | | Typical adult, no heart/kidney failure | 500–1,000 mL/h initially for 2–4 h, then reduce/individualize | | Older adult, heart failure, advanced kidney disease | Smaller boluses (e.g., **250 mL**) with lung/JVP/POCUS/urine-output reassessment[2] | | Glucose <250 mg/dL but DKA persists | Add **5–10% dextrose** while continuing insulin[2] | **Do not chase glucose alone.** Fluid therapy lowers glucose even before insulin by improving renal perfusion and decreasing counterregulatory stress. --- #### 2. Insulin Insulin suppresses lipolysis and ketogenesis; this is the definitive metabolic treatment. ##### IV insulin For severe DKA or when close titration is needed: - regular insulin infusion typically **0.1 units/kg/hour**[1,2] - a routine IV bolus is not required in many modern protocols - continue insulin after glucose reaches the target range by adding dextrose rather than stopping insulin prematurely When glucose falls below **250 mg/dL**, add dextrose and adjust insulin to keep glucose roughly around 200 mg/dL until ketoacidosis has resolved.[2] ##### Subcutaneous rapid-acting insulin **Uncomplicated mild and selected moderate DKA** can be managed with subcutaneous rapid-acting insulin analogues every 1–2 hours in systems with adequate nursing, protocolization, electrolyte monitoring, and ability to escalate.[1,2] Do **not** use subcutaneous pathways for severe DKA, shock, HHS, pregnancy without a dedicated protocol, major comorbidity, impaired perfusion, or inability to monitor closely. --- #### 3. Potassium: the highest-risk electrolyte issue Total-body potassium is depleted even when the initial serum level is high. | Serum K⁺ | Action | |---|---| | **<3.5 mmol/L** | **Hold insulin.** Begin potassium replacement; the 2024 consensus summary recommends about **10 mmol/hour** until K⁺ >3.5 mmol/L, with ECG/serial monitoring and local infusion-safety rules.[2] | | **3.5 to <5.0 mmol/L** | Start insulin and give potassium in IV fluids; titrate to maintain **4–5 mmol/L** | | **≥5.0 mmol/L** | Do not routinely give potassium initially; monitor closely because it will usually fall rapidly after fluids/insulin | Check potassium at baseline, approximately 2 hours after insulin starts, and at least every 4 hours until resolution; more often when abnormal or replacing aggressively.[2] **Board pearl:** Starting insulin in profound hypokalemia can precipitate malignant arrhythmia and respiratory muscle weakness. --- #### 4. Bicarbonate **Routine bicarbonate is not recommended.** It does not improve routine DKA outcomes and may worsen hypokalemia and cause other adverse effects.[1] Consider bicarbonate only for **severe acidosis (pH <7.0)**. The 2024 consensus describes **100 mmol sodium bicarbonate in 400 mL sterile water**, repeatable every 2 hours until pH >7.0 if indicated.[1] Use local critical-care/endocrine protocols because sodium load, potassium shifts, and volume status matter. --- #### 5. Phosphate and magnesium Routine phosphate replacement is not recommended. Consider replacement when phosphate is markedly low—particularly **<1.0 mmol/L** in the setting of muscle weakness or cardiac/respiratory impairment—using local dosing and calcium monitoring.[2] Magnesium should be measured and replaced when low, especially with arrhythmia or refractory hypokalemia. --- #### 6. Treat the precipitating cause - infection → appropriate antimicrobials/source control when indicated - MI/stroke → activate disease-specific pathway - insulin access/omission → correct access and education barriers - pump failure → reliable subcutaneous/IV insulin first; troubleshoot device later - SGLT2-associated DKA → discontinue drug during the event --- ### Monitoring and reassessment During active treatment, the 2024 consensus recommends:[2] - bedside glucose every **1–2 hours** - electrolytes, creatinine, phosphate, β-hydroxybutyrate, and venous pH approximately every **4 hours** until resolution - continuous/frequent vital signs - strict fluid balance and urine output - ECG monitoring when potassium is abnormal, severe illness is present, or cardiac disease is suspected #### What improvement should look like - decreasing β-hydroxybutyrate - rising bicarbonate/pH - improved perfusion and mental status - controlled fall in glucose - correction of potassium deficit without hypokalemia #### Anticipate treatment complications | Complication | Why it happens | Prevention/response | |---|---|---| | **Hypoglycemia** | Insulin continues while glucose falls | Add dextrose before ketosis resolves; frequent glucose checks | | **Hypokalemia** | Insulin + correction of acidosis shifts K intracellularly | Scheduled potassium monitoring/replacement | | **Hyperchloremic acidosis** | Chloride-rich fluids + urinary ketoanion loss | Prefer balanced crystalloids when appropriate; interpret residual low bicarbonate carefully | | **Fluid overload** | Aggressive resuscitation in HF/CKD/older patients | Smaller boluses; frequent clinical/POCUS reassessment | | **Cerebral edema** | Rare in adults; rapid osmotic shifts are a concern | Avoid overly rapid correction, especially in mixed DKA/HHS; urgent critical-care/neuro treatment if suspected | | **Thrombosis** | Severe dehydration/hyperosmolarity, especially HHS overlap | Standard VTE risk assessment/prophylaxis when appropriate | --- ### Resolution and transition to subcutaneous insulin Do not define resolution by glucose alone. Modern practice emphasizes **suppression of ketonemia**.[2,3] Practical resolution requires clinical recovery plus normalization of the ketoacid state, generally with: - β-hydroxybutyrate falling to the normal/near-normal range (the consensus centers direct ketone measurement), and - pH/bicarbonate recovery Where β-hydroxybutyrate is unavailable, anion gap normalization remains a useful surrogate, but beware hyperchloremic acidosis.[3] #### Transition - Estimate total daily insulin based on preadmission therapy, weight, and in-hospital requirements. - A typical insulin-naïve estimate is approximately **0.3–0.6 units/kg/day**, individualized for frailty, renal function, steroid use, obesity, and hypoglycemia risk.[2] - Use a **basal-bolus** strategy where appropriate. - Give basal insulin **at least 1–2 hours before** stopping IV insulin to prevent rebound hyperglycemia/recurrent ketosis.[2] Continuing an established basal insulin dose during IV DKA therapy is reasonable in many patients and may reduce rebound hyperglycemia.[2] --- ### Differential diagnosis | Condition | Distinguishing features | |---|---| | **HHS** | Glucose ≥600 mg/dL, hyperosmolality, minimal ketonemia/acidosis; overlap is common | | **Starvation ketoacidosis** | Low intake, usually lower glucose and milder ketonemia/acidosis; insulin deficiency is not the primary driver | | **Alcoholic ketoacidosis** | Heavy alcohol use, vomiting, low/normal glucose, elevated β-hydroxybutyrate; thiamine and nutrition are important | | **Lactic acidosis** | Elevated lactate; shock, sepsis, hypoxia, toxins, metformin accumulation among causes | | **Toxic alcohols** | Osmolar gap early, neurologic/visual/renal clues; specific antidotal/toxicology pathway | | **Salicylate toxicity** | Mixed respiratory alkalosis + AG acidosis, tinnitus, hyperventilation | | **Uremic acidosis** | Advanced kidney failure; ketones not diagnostic of DKA unless coexisting | --- ### DKA versus HHS | Feature | DKA | HHS | |---|---|---| | Glucose | ≥200 mg/dL or known diabetes; may be euglycemic | Usually ≥600 mg/dL | | Ketones | β-hydroxybutyrate ≥3 mmol/L | <3 mmol/L by definition | | pH | <7.3 and/or HCO3 <18 | pH ≥7.3 and HCO3 ≥15 | | Osmolality | Variable | Effective >300 or total >320 mOsm/kg | | Dominant pathophysiology | Ketogenesis + acidosis | Profound dehydration + hyperosmolality | | Insulin infusion | Commonly 0.1 U/kg/h severe DKA | Typically 0.05 U/kg/h; **0.1 U/kg/h if mixed DKA/HHS**[2] | One-third of hyperglycemic crises may have overlapping features; treat significant ketosis/acidosis as DKA while also respecting HHS limits on the rate of osmotic correction.[1,2] --- ### Special populations #### SGLT2 inhibitor users SGLT2 inhibitors increase the risk of euglycemic DKA. During severe illness, prolonged fasting, ketonemia/ketonuria, and surgery they should be withheld. ADA 2026 hospital standards recommend stopping SGLT2 inhibitors **3 days before scheduled surgery and 4 days for ertugliflozin**.[4] After an episode, reassess the indication and individual risk before restarting; ensure adequate intake and resolution of precipitating factors. #### Pregnancy Pregnancy increases susceptibility to ketosis and DKA can occur at lower glucose concentrations. Maternal DKA threatens fetal oxygenation and perfusion. Priorities are maternal fluids, insulin, electrolyte correction, trigger treatment, and early obstetric/endocrine involvement. Do not delay maternal stabilization for fetal interventions. #### Advanced CKD/dialysis Volume deficit may be smaller or absent, potassium can be dangerously high, and insulin clearance is reduced. Standard large-volume protocols can cause pulmonary edema. Use individualized fluids, potassium strategy, and nephrology/critical-care input. #### Older adults / heart failure Use smaller aliquots of fluid with frequent reassessment; avoid reflexive “protocol liters.”[2] #### Insulin pumps / automated insulin delivery Pump interruption can produce DKA quickly because many pump users have no long-acting insulin depot. During active DKA, use a reliable protocolized insulin route; inspect the infusion set and device, and re-establish pump therapy only after metabolic stabilization and competency assessment. --- ### Prevention and discharge bundle Every DKA admission should trigger a search for preventable causes.[1] Before discharge: - reconcile insulin regimen and supplies - confirm access to insulin, needles/pens, glucose monitoring, ketone testing - teach sick-day rules - explain when to check blood ketones - never stop basal insulin in type 1 diabetes because of poor appetite alone - provide clear hydration/carbohydrate guidance during illness - review pump failure backup plan - review SGLT2 sick-day/perioperative plan - address mental health, diabetes distress, substance use, food insecurity, or cost barriers - arrange prompt diabetes follow-up, especially after recurrent DKA --- ### Current guideline changes and controversies #### STANDARD OF CARE - β-hydroxybutyrate is the preferred ketone test for diagnosis and monitoring.[1,3] - Diagnostic glucose threshold is now **≥200 mg/dL or established diabetes**, acknowledging euglycemic DKA.[1] - Balanced crystalloids are reasonable and increasingly favored when available.[1,2] - Mild/uncomplicated moderate DKA may be treated with protocolized subcutaneous rapid-acting insulin rather than mandatory ICU IV insulin.[1,2] - Routine bicarbonate/phosphate therapy is not recommended.[1,2] #### EMERGING EVIDENCE - Broader adoption of point-of-care β-hydroxybutyrate may shorten time to resolution and reduce inappropriate reliance on urine ketones.[3] - Continuous ketone monitoring and integration with diabetes technology are active research areas.[1] - Evidence continues to refine which moderate-DKA patients can safely avoid ICU care. #### EXPERIMENTAL / INVESTIGATIONAL - Continuous interstitial ketone sensors - algorithmic integration of CGM + ketones + automated insulin delivery for early DKA prevention - novel fluid/electrolyte protocols in severe renal/cardiac comorbidity --- ### Acute management checklist #### Recognition - [ ] Glucose/known diabetes criterion - [ ] β-hydroxybutyrate ≥3 mmol/L or urine ketones ≥2+ - [ ] pH <7.3 and/or bicarbonate <18 - [ ] Check for HHS overlap / osmolality #### Immediate treatment - [ ] IV access and isotonic/balanced crystalloid - [ ] Baseline potassium before insulin - [ ] IV insulin 0.1 U/kg/h for severe DKA, or validated SC protocol for selected mild/moderate cases - [ ] Add dextrose when glucose <250 mg/dL while insulin continues - [ ] Potassium replacement targeted to 4–5 mmol/L - [ ] No routine bicarbonate or phosphate - [ ] Identify/treat precipitant #### Monitoring - [ ] Glucose every 1–2 h - [ ] Electrolytes, creatinine, β-hydroxybutyrate, pH about every 4 h - [ ] ECG/telemetry if indicated - [ ] Fluid balance/urine output - [ ] Repeat neurologic/respiratory assessment #### Transition - [ ] Ketoacidosis resolved—not just glucose normalized - [ ] Basal insulin given 1–2 h before IV infusion stops - [ ] Prevention plan and supplies arranged --- ### Diagnostic/management algorithm ```text Symptoms compatible with hyperglycemic crisis ↓ Glucose + β-hydroxybutyrate + venous pH/HCO3 + electrolytes ↓ DKA criteria all present? D: glucose ≥200 mg/dL OR known diabetes K: β-hydroxybutyrate ≥3 mmol/L A: pH <7.3 and/or HCO3 <18 ↓ Yes → assess severity + HHS overlap + precipitant ↓ Fluids + potassium strategy + insulin + cause-specific treatment ↓ K <3.5? ├─ Yes → replace K, HOLD insulin until >3.5 └─ No → start insulin ↓ Glucose <250 before ketoacidosis resolves? ├─ Yes → add 5–10% dextrose, CONTINUE insulin └─ No → continue protocol ↓ Serial β-hydroxybutyrate / pH / electrolytes / glucose ↓ Ketoacidosis resolved + patient clinically stable ↓ Basal-bolus insulin overlap → discharge prevention bundle ``` --- ### Common pitfalls | Pitfall | Why it is wrong | Better approach | |---|---|---| | “Glucose is 170, so this cannot be DKA.” | Euglycemic DKA exists, especially with SGLT2 inhibitors | Check β-hydroxybutyrate and acid-base status | | Following urine ketones to resolution | Urine nitroprusside measures acetoacetate, not β-hydroxybutyrate | Prefer quantitative blood β-hydroxybutyrate | | Starting insulin with K⁺ 2.9 mmol/L | Can trigger life-threatening hypokalemia | Replace K first; start insulin after K >3.5 | | Stopping insulin once glucose normalizes | Ketogenesis may persist | Add dextrose and continue insulin until DKA resolves | | Treating every adult with several liters rapidly | HF/CKD/older adults may overload | Individualized boluses and frequent reassessment | | Using anion gap alone to declare persistent DKA | Hyperchloremic acidosis can persist after ketones clear | Track β-hydroxybutyrate when available | | Giving bicarbonate routinely | No routine outcome benefit; potential harm | Reserve for severe acidosis, generally pH <7.0 | --- ## Exam-focused review ### Foundation / USMLE Step 1 Know the biochemical sequence: **↓ insulin + ↑ glucagon → lipolysis → free fatty acids → hepatic ketogenesis → β-hydroxybutyrate/acetoacetate → metabolic acidosis.** Despite total-body potassium depletion, serum potassium may be high initially because insulin deficiency and acidosis shift potassium extracellularly. ### USMLE Step 2 CK Classic next-best-step questions: - DKA + K⁺ 2.9 → **potassium before insulin**. - DKA + glucose falls to 220 while gap/ketones persist → **add dextrose and continue insulin**. - SGLT2 user + acidosis/ketones + glucose 160 → **euglycemic DKA**. - Severe DKA + hypotension → **fluids first while preparing insulin/electrolyte management**. ### Step 3 / Resident Think systems: - determine appropriate level of care - identify and treat precipitant - avoid protocol-induced fluid overload - ensure basal insulin overlap - prevent recurrence through medication access, education, and device troubleshooting ### MRCP / ABIM / Board level High-yield distinctions: - β-hydroxybutyrate is preferred over urine ketones - mixed acid-base disorders can mask acidemia - persistent low bicarbonate after ketone clearance may reflect hyperchloremic acidosis - DKA/HHS overlap should be treated with DKA-level insulin while controlling osmotic correction --- ### Original MCQs #### Question 1 A 32-year-old woman with type 1 diabetes presents with vomiting and abdominal pain. Glucose is 390 mg/dL, pH 7.18, bicarbonate 12 mmol/L, β-hydroxybutyrate 5.8 mmol/L, and potassium 2.9 mmol/L. What is the most appropriate immediate metabolic treatment? A. Start insulin infusion immediately B. Administer sodium bicarbonate C. Begin potassium replacement and fluids; delay insulin until potassium is >3.5 mmol/L D. Give subcutaneous basal insulin only E. Restrict fluids **Answer: C.** Severe hypokalemia makes immediate insulin dangerous because insulin will shift potassium intracellularly and can precipitate arrhythmia or respiratory muscle weakness.[2] #### Question 2 A patient with DKA has received fluids and insulin for 5 hours. Glucose has fallen from 520 to 230 mg/dL, but β-hydroxybutyrate remains 3.8 mmol/L and bicarbonate is 14 mmol/L. What should happen next? A. Stop insulin because glucose is now <250 mg/dL B. Add dextrose-containing fluid and continue insulin C. Give bicarbonate routinely D. Switch to oral metformin E. Give glucagon **Answer: B.** Glucose often normalizes before ketogenesis stops. Dextrose permits ongoing insulin therapy without causing hypoglycemia.[2] #### Question 3 A 66-year-old with type 2 diabetes taking empagliflozin presents after poor oral intake with nausea and tachypnea. Glucose is 178 mg/dL, bicarbonate 13 mmol/L, pH 7.22, and β-hydroxybutyrate 4.7 mmol/L. Which diagnosis is most likely? A. HHS B. Lactic acidosis only C. Euglycemic DKA D. Respiratory alkalosis E. Starvation ketosis without diabetes-related ketoacidosis **Answer: C.** The combination of significant ketonemia and metabolic acidosis in an SGLT2 inhibitor user is classic for euglycemic DKA.[1,4] #### Question 4 Which parameter is preferred for monitoring biochemical resolution of DKA when available? A. Urine ketone color intensity B. Serum chloride alone C. Quantitative blood β-hydroxybutyrate D. HbA1c E. Serum osmolar gap **Answer: C.** β-hydroxybutyrate directly reflects the dominant circulating ketone and avoids misleading urine-ketone behavior during recovery.[1,3] #### Question 5 A 78-year-old with DKA, HFrEF, and CKD is hypotensive but has pulmonary crackles after 1 L crystalloid. What is the best principle for ongoing fluid management? A. Continue 1 L/hour regardless of examination B. Stop all fluid and insulin C. Use smaller boluses with frequent hemodynamic/lung reassessment and individualized shock management D. Give free water only E. Administer bicarbonate instead of fluid **Answer: C.** Contemporary guidance recommends smaller aliquots in older adults and those with heart/kidney failure, with repeated reassessment.[2] --- ### References 1. Umpierrez GE, Davis GM, ElSayed NA, et al. **Hyperglycemic Crises in Adults With Diabetes: A Consensus Report.** *Diabetes Care.* 2024;47(8):1257-1275. doi:10.2337/dci24-0032. PMID:39052901. https://diabetesjournals.org/care/article/47/8/1257/156808/Hyperglycemic-Crises-in-Adults-With-Diabetes-A 2. Morey-Vargas OL, et al. **Hyperglycemic Crises in Adults: The 2024 Consensus Report.** Cleveland Clinic Journal of Medicine/Consult QD summary, 2025. https://consultqd.clevelandclinic.org/hyperglycemic-crises-in-adults-the-2024-consensus-report 3. Cleveland Clinic review of the 2024 consensus criteria and monitoring changes, including β-hydroxybutyrate-based diagnosis/resolution. https://consultqd.clevelandclinic.org/hyperglycemic-crises-in-adults-the-2024-consensus-report 4. American Diabetes Association Professional Practice Committee. **16. Diabetes Care in the Hospital: Standards of Care in Diabetes—2026.** *Diabetes Care.* 2026;49(Suppl 1):S339-. https://diabetesjournals.org/care/article/49/Supplement_1/S339/163925/16-Diabetes-Care-in-the-Hospital-Standards-of-Care 5. Alghamdi NA, Major P, Chaudhuri D, et al. **Saline compared to balanced crystalloid in patients with diabetic ketoacidosis: a systematic review and meta-analysis of randomized controlled trials.** *Crit Care Explor.* 2022;4(1):e0613. 6. Self WH, Evans CS, Jenkins CA, et al. **Clinical effects of balanced crystalloids vs saline in adults with diabetic ketoacidosis: a subgroup analysis of cluster randomized clinical trials.** *JAMA Netw Open.* 2020;3(11):e2024596. doi:10.1001/jamanetworkopen.2020.24596. 7. Kilpatrick ES, Butler AE, Ostlundh L, Atkin SL, Sacks DB. **Controversies around the measurement of blood ketones to diagnose and manage diabetic ketoacidosis.** *Diabetes Care.* 2022;45(2):267-272. 8. Kamel KS, Halperin ML. **Acid-base problems in diabetic ketoacidosis.** *N Engl J Med.* 2015;372:546-554. 9. American Diabetes Association Professional Practice Committee. **9. Pharmacologic Approaches to Glycemic Treatment: Standards of Care in Diabetes—2026.** *Diabetes Care.* 2026;49(Suppl 1):S183-. https://diabetesjournals.org/care/article/49/Supplement_1/S183/163934/9-Pharmacologic-Approaches-to-Glycemic-Treatment 10. Cao S, Cao S. **Comment on Umpierrez et al. Hyperglycemic Crises in Adults With Diabetes.** *Diabetes Care.* 2025;48(3):e40-e41. doi:10.2337/dc24-2296. PMID:39977634. --- **Next linked topics:** Hyperosmolar hyperglycemic state; hypoglycemia; insulin therapy in hospital; SGLT2 inhibitor adverse effects; acid-base disorders; potassium disorders; diabetes sick-day management.1e:T71d1,## Summary Dyslipidemia is an abnormal concentration or composition of circulating lipoproteins that increases atherosclerotic cardiovascular disease (ASCVD) risk or, when triglycerides are very high, pancreatitis risk. LDL-containing apoB particles are causally related to atherosclerosis; treatment therefore focuses on reducing cumulative exposure to atherogenic lipoproteins while addressing triglyceride-rich particles, lipoprotein(a) [Lp(a)], diabetes, blood pressure, smoking, obesity, kidney disease, and other risk determinants.[1-4] The 2026 ACC/AHA multisociety guideline replaced the 2018 US cholesterol guideline. Major changes include use of PREVENT-ASCVD equations in primary prevention, explicit LDL-C and non-HDL-C goals, at-least-once lifetime Lp(a) measurement, selective apoB measurement, broader use of coronary artery calcium (CAC), and earlier treatment when lifetime exposure is concerning.[1-3] In adults aged 30–79 years without known ASCVD or subclinical atherosclerosis and with LDL-C 70–189 mg/dL, 10-year PREVENT-ASCVD risk is categorized as low (<3%), borderline (3% to <5%), intermediate (5% to <10%), or high (≥10%). LDL-lowering therapy can be considered at borderline risk, should be considered at intermediate risk after shared decision-making, and high-intensity statin therapy is recommended when treatment is initiated at high risk.[1-3] For primary prevention after treatment is chosen, the 2026 US guideline uses LDL-C goals of <100 mg/dL for borderline/intermediate risk and <70 mg/dL for high risk. In secondary prevention, LDL-C <55 mg/dL is recommended for very-high-risk ASCVD and <70 mg/dL for ASCVD not meeting very-high-risk criteria.[1-3] European guidance remains risk-category based; the 2025 ESC/EAS focused update retains the 2019 LDL-C targets and emphasizes rapid intensification, risk modifiers, Lp(a), imaging-defined subclinical atherosclerosis, bempedoic acid for statin intolerance, and earlier combination therapy after acute coronary syndrome.[4,5] Statins remain first-line pharmacotherapy. If the required LDL-C reduction or goal is not achieved, add evidence-based nonstatin therapy according to absolute risk, the size of the remaining LDL-C gap, tolerability, cost/access, and comorbidity. Ezetimibe and PCSK9 monoclonal antibodies have cardiovascular-outcome evidence; bempedoic acid has outcome data in statin-intolerant patients. Inclisiran produces substantial LDL-C lowering, but definitive cardiovascular-outcome data remain pending as of the evidence date.[1-3,6-10] > **Clinical pearl:** Treat the patient's risk, not an isolated lipid number. A modest LDL-C elevation can warrant treatment in established ASCVD, while a higher LDL-C in a young low-short-term-risk adult may require lifetime-risk thinking, family history assessment, and evaluation for familial hypercholesterolemia. ## Lipoprotein physiology and why it matters Cholesterol and triglycerides are transported in lipoproteins. ApoB-containing particles include chylomicron remnants, VLDL, IDL, LDL, and Lp(a). Each atherogenic particle generally carries one apoB molecule, so apoB approximates the number of circulating atherogenic particles. LDL-C measures the cholesterol mass within LDL particles; discordance can occur when particles are cholesterol-depleted, particularly with hypertriglyceridemia, diabetes, metabolic disease, or very low treated LDL-C.[1,2] ### LDL and atherosclerosis Atherosclerosis develops when apoB-containing particles enter and are retained in the arterial intima, triggering lipid accumulation, inflammation, plaque formation, remodeling, and eventually rupture or erosion. Genetic, epidemiologic, and randomized-treatment evidence supports a causal relationship between cumulative LDL exposure and ASCVD.[1,2] ### Triglyceride-rich lipoproteins Triglycerides are carried primarily in chylomicrons and VLDL. Mild-to-moderate hypertriglyceridemia often marks increased remnant cholesterol, insulin resistance, obesity, diabetes, alcohol exposure, or secondary disease. Severe hypertriglyceridemia, particularly ≥1000 mg/dL (11.3 mmol/L), can produce chylomicronemia and substantially increase acute pancreatitis risk.[1-3] ### Lipoprotein(a) Lp(a) is an LDL-like particle linked to apolipoprotein(a). Concentration is largely genetically determined, varies markedly between individuals, and is minimally changed by lifestyle. The 2026 ACC/AHA guideline recommends measurement at least once in adulthood. Lp(a) ≥125 nmol/L (approximately 50 mg/dL) is a risk-enhancing level; ≥250 nmol/L (approximately 100 mg/dL) is associated with roughly twice the estimated long-term ASCVD risk compared with low levels.[2,3] ## Classification Dyslipidemia may be primary, secondary, or mixed. | Pattern | Typical laboratory finding | Common causes | Main clinical concern | |---|---|---|---| | Isolated LDL-C elevation | High LDL-C | Polygenic hypercholesterolemia, familial hypercholesterolemia, hypothyroidism, nephrotic syndrome | ASCVD | | Mixed dyslipidemia | High LDL-C/non-HDL-C plus high triglycerides | Diabetes, metabolic disease, obesity, CKD, alcohol, familial combined hyperlipidemia | ASCVD; pancreatitis if triglycerides become severe | | Predominant hypertriglyceridemia | High triglycerides, variable LDL-C | Diabetes, alcohol, obesity, medications, familial disorders | ASCVD and/or pancreatitis | | Low HDL-C | Low HDL-C, often high triglycerides | Insulin resistance, smoking, obesity, inflammatory states | Risk marker; HDL-raising drugs are not a treatment target | | Elevated Lp(a) | High Lp(a), often normal standard lipid profile | Genetic | ASCVD and calcific aortic valve disease risk | | Severe inherited dyslipidemia | Very high LDL-C or triglycerides from early life | HeFH/HoFH, familial chylomicronemia syndrome | Premature ASCVD or recurrent pancreatitis | ## Causes and secondary contributors Before labeling a disorder as primary, identify reversible contributors. ### Common secondary causes of high LDL-C - hypothyroidism; - nephrotic syndrome; - cholestatic liver disease; - uncontrolled diabetes in some phenotypes; - pregnancy; - medications such as cyclosporine, some antiretrovirals, retinoids, and selected hormonal therapies. ### Common secondary causes of high triglycerides - poorly controlled diabetes; - obesity and insulin resistance; - high alcohol intake; - diets with substantial refined carbohydrate or excess caloric intake; - pregnancy; - hypothyroidism; - CKD or nephrotic syndrome; - glucocorticoids, oral estrogens, retinoids, atypical antipsychotics, some HIV therapies, some immunosuppressants, and other drugs. A secondary cause can amplify an inherited tendency. Severe triglyceride elevation often results from several factors acting together rather than one single disorder. ## Clinical presentation Most patients are asymptomatic until an ASCVD event occurs. Severe inherited disorders may produce physical clues. ### Findings suggesting inherited hypercholesterolemia - tendon xanthomas, particularly Achilles or extensor tendons; - premature corneal arcus; - family history of markedly elevated LDL-C; - premature coronary, cerebrovascular, or peripheral atherosclerotic disease; - LDL-C ≥190 mg/dL (4.9 mmol/L), especially when persistent and unexplained. ### Findings suggesting severe hypertriglyceridemia - eruptive xanthomas; - lipemia retinalis; - recurrent pancreatitis; - abdominal pain in a patient with extreme triglyceride elevation. > **Caution:** Acute pancreatitis can transiently alter lipid measurements. If severe hypertriglyceridemia is suspected as the cause, obtain triglycerides early in the presentation when feasible. ## Initial assessment ### History Clarify: - prior lipid values and age at first abnormal result; - personal history of coronary, cerebrovascular, peripheral, or aortic atherosclerotic disease; - diabetes, hypertension, CKD, HIV, inflammatory disease, obesity, smoking, and sleep-related breathing disorders; - diet, alcohol, physical activity, and weight trajectory; - family history of premature ASCVD or known inherited dyslipidemia; - current medications and supplements; - pregnancy plans or lactation; - prior lipid-lowering therapies, adherence, adverse effects, and reasons for discontinuation. ### Baseline laboratory assessment For most adults obtain a standard lipid profile: total cholesterol, HDL-C, triglycerides, and calculated or directly measured LDL-C. A fasting sample is not required for routine risk assessment, but fasting testing is useful when triglycerides are substantially elevated, when pancreatitis risk is being assessed, or when calculation accuracy is poor.[1] Additional testing is guided by context: - HbA1c or fasting glucose; - TSH when hypothyroidism is possible; - creatinine/eGFR and urine protein when kidney disease is possible; - hepatic panel before or during therapy when clinically indicated; - Lp(a) at least once in adulthood; - apoB when particle-number information may change management, particularly with triglycerides ≥150 mg/dL, diabetes, cardiometabolic disease, known ASCVD, or very low achieved LDL-C.[1-3] ## Interpreting the lipid profile ### LDL-C LDL-C is the principal treatment marker for most patients. Calculation methods are less reliable at high triglyceride concentrations; laboratories may use newer validated equations or direct measurement. If a result is inconsistent with the clinical picture, repeat testing and review the method used. ### Non-HDL-C Non-HDL-C = total cholesterol − HDL-C. It captures cholesterol within all apoB-containing particles and is useful when triglycerides are elevated. The 2026 US guideline again uses non-HDL-C goals alongside LDL-C goals.[1] ### ApoB ApoB can uncover residual particle burden when LDL-C appears acceptable but triglycerides, diabetes, obesity, or metabolic disease suggest cholesterol-depleted particles. It is an adjunct, not a replacement for standard risk assessment in every patient.[1] ### Lp(a) Lp(a) should generally be measured once because levels are genetically determined and relatively stable. Repeat testing can be reasonable when a major inflammatory state, nephrotic syndrome, or another condition likely to alter the value has resolved, or when an assay-related concern exists. ## ASCVD risk assessment in primary prevention ### 2026 US framework For adults aged 30–79 years without clinical ASCVD or known subclinical atherosclerosis and with LDL-C 70–189 mg/dL, the 2026 ACC/AHA guideline uses PREVENT-ASCVD equations.[1-3] | 10-year PREVENT-ASCVD risk | Category | General approach when LDL-C is 70–189 mg/dL | |---|---|---| | <3% | Low | Lifestyle; consider lifetime/30-year risk and special indications | | 3% to <5% | Borderline | LDL-lowering therapy can be considered after personalization | | 5% to <10% | Intermediate | LDL-lowering therapy should be considered after shared decision-making | | ≥10% | High | High-intensity statin therapy when treatment is initiated; aim for ≥50% LDL-C reduction and LDL-C <70 mg/dL | Important situations are managed outside a simple risk-calculator pathway. LDL-lowering therapy is recommended for many adults aged 40–75 years with diabetes, stage 3–4 CKD, or HIV regardless of baseline LDL-C. Persistent LDL-C ≥190 mg/dL strongly suggests severe primary hypercholesterolemia and generally warrants intensive therapy without relying on short-term risk calculation.[1-3] ### Risk personalization Factors not fully captured by a calculator can alter treatment decisions, including: - family history of premature ASCVD; - LDL-C 160–189 mg/dL in younger adults; - elevated Lp(a); - inflammatory disease; - selected reproductive or pregnancy-related risk markers; - chronic kidney or metabolic disease; - persistently elevated triglycerides; - imaging evidence of subclinical atherosclerosis. ### Coronary artery calcium CAC is most useful when a treatment decision remains uncertain. The 2026 US guideline supports selective CAC use in men ≥40 years and women ≥45 years with borderline or intermediate risk. Any CAC supports an LDL-C goal <100 mg/dL, with progressively lower goals as CAC burden rises; CAC ≥1000 is treated as a very-high subclinical atherosclerosis burden with an LDL-C goal <55 mg/dL.[1-3] CAC = 0 can support deferring pharmacotherapy in selected lower-risk adults, but it should not override strong indications such as severe hypercholesterolemia, diabetes in many patients, active smoking, or a strong premature-family-history signal. ## Treatment goals ### 2026 ACC/AHA goals | Clinical setting | LDL-C goal | Non-HDL-C goal | Typical treatment intensity | |---|---:|---:|---| | Primary prevention, borderline/intermediate risk after treatment chosen | <100 mg/dL | <130 mg/dL | Usually moderate-intensity statin; individualize | | Primary prevention, high risk | <70 mg/dL | <100 mg/dL | High-intensity statin; ≥50% LDL-C reduction | | Clinical ASCVD, not very high risk | <70 mg/dL | <100 mg/dL | High-intensity/maximally tolerated statin plus add-on therapy as needed | | Clinical ASCVD, very high risk | <55 mg/dL | <85 mg/dL | Early combination therapy often required | The absolute goal and expected percentage reduction should both be considered. A patient starting at LDL-C 220 mg/dL may require combination therapy even after a large percentage reduction.[1-3] ### European approach The 2025 ESC/EAS update retained the 2019 risk-based LDL-C targets while updating how risk is refined and how therapy is intensified. SCORE2/SCORE2-OP, subclinical atherosclerosis, CAC, Lp(a), and earlier combination therapy are emphasized. Lp(a) >50 mg/dL (>105 nmol/L in the ESC document) can act as a risk modifier. Bempedoic acid is incorporated for patients who cannot take statins and as add-on therapy in selected high/very-high-risk patients.[4,5] > **Current practice:** US and European systems use different risk calculators and category definitions. Do not mix a European risk category with a US treatment threshold without reconciling the underlying framework. ## Lifestyle treatment Lifestyle therapy is foundational but should not delay pharmacotherapy when absolute risk is high. ### Dietary pattern Favor: - vegetables, fruit, legumes, whole grains, nuts, seeds; - fish and other minimally processed protein sources; - replacement of saturated fat with unsaturated fats; - high-fiber foods; - reduction in trans fat, refined carbohydrate, and highly processed foods. For severe hypertriglyceridemia, management is more urgent and often requires a very-low-fat diet, elimination of alcohol, correction of hyperglycemia, and specialist dietetic support.[1] ### Weight, activity, smoking, alcohol - Achieve and maintain a healthy weight when overweight or obesity is present. - Use regular aerobic and resistance activity adapted to functional status. - Stop tobacco and nicotine exposure. - Limit or eliminate alcohol when triglycerides are elevated; eliminate alcohol in severe hypertriglyceridemia until controlled. Dietary supplements should not be used as substitutes for evidence-based LDL-lowering pharmacotherapy.[1] ## Pharmacotherapy ### Statins Statins inhibit HMG-CoA reductase, increase hepatic LDL-receptor activity, lower LDL-C, and reduce cardiovascular events. They remain the first-line drug class for most ASCVD prevention.[1] | Intensity | Expected LDL-C reduction | Common regimens | |---|---:|---| | High | ≥50% | Atorvastatin 40–80 mg daily; rosuvastatin 20–40 mg daily | | Moderate | 30–49% | Atorvastatin 10–20 mg; rosuvastatin 5–10 mg; simvastatin 20–40 mg; pravastatin 40–80 mg; pitavastatin 1–4 mg; fluvastatin XL 80 mg | | Low | <30% | Lower-dose pravastatin, simvastatin, lovastatin, or fluvastatin regimens | The ACC Lipid Manager based on the 2026 guideline lists atorvastatin 40–80 mg and rosuvastatin 20–40 mg as high-intensity regimens.[11] #### Monitoring Obtain a baseline lipid profile and repeat after therapy initiation or dose change, commonly within 4–12 weeks, then at intervals appropriate to risk and adherence. Routine CK monitoring is unnecessary in asymptomatic patients. Check CK when severe muscle symptoms or weakness occur; investigate alternative causes such as hypothyroidism, strenuous activity, or interacting drugs. #### Statin-associated symptoms Muscle symptoms should be assessed systematically rather than assuming a class-wide intolerance. Consider: - temporal relationship to starting/stopping therapy; - interacting drugs; - thyroid disease, vitamin or metabolic abnormalities when clinically plausible; - rechallenge with a different statin; - lower dose or alternate dosing schedule; - combination therapy using a tolerated statin dose plus a nonstatin. Complete inability to tolerate any statin is less common than partial intolerance. ### Ezetimibe Ezetimibe reduces intestinal cholesterol absorption and typically lowers LDL-C by an additional 15–25% when added to a statin. It has cardiovascular-outcome evidence after acute coronary syndrome and is often the first oral add-on when the LDL-C gap is modest or cost/access favors it.[6] Typical adult dose: **10 mg orally once daily**. ### PCSK9 monoclonal antibodies Alirocumab and evolocumab markedly reduce LDL-C, commonly by roughly 45–65% depending on background therapy, and reduce ASCVD events in high-risk populations.[7,8,12] They are particularly useful when: - ASCVD risk is very high and LDL-C remains well above goal; - familial hypercholesterolemia is present; - a large additional LDL-C reduction is needed; - statin intolerance limits oral therapy. ### Bempedoic acid Bempedoic acid inhibits ATP citrate lyase upstream of HMG-CoA reductase. CLEAR Outcomes demonstrated cardiovascular benefit in statin-intolerant patients.[9] The 2025 ESC/EAS update recommends it in patients unable to take statins to achieve LDL-C goals and supports add-on use in selected high/very-high-risk patients.[4,5] Typical adult dose: **180 mg orally once daily**. Important adverse effects include hyperuricemia/gout and a small risk of tendon injury; review labeling and interactions before prescribing. ### Inclisiran Inclisiran is a small-interfering RNA therapy that suppresses hepatic PCSK9 synthesis and produces substantial LDL-C lowering with infrequent maintenance dosing. As of September 2026, the 2026 ACC/AHA guideline notes that cardiovascular-outcome trials are still pending; use is therefore based on LDL-C-lowering efficacy, adherence considerations, approved indications, and local policy rather than proven event reduction comparable to PCSK9 monoclonal antibodies.[1,3] ### Specialized agents Evinacumab, lomitapide, LDL apheresis, and other specialized strategies are used mainly in severe familial disorders, especially homozygous familial hypercholesterolemia, under lipid-specialist care.[1] ## Hypertriglyceridemia ### Triglycerides 150–499 mg/dL Priorities are: 1. identify and treat secondary causes; 2. optimize weight, glycemic control, diet, and alcohol intake; 3. use statin therapy according to ASCVD risk; 4. consider icosapent ethyl in selected high-risk patients with persistent triglyceride elevation despite statin therapy.[1,4,10] The 2025 ESC/EAS update supports icosapent ethyl **2 g twice daily** with a statin in selected high/very-high-risk patients with fasting triglycerides 135–499 mg/dL to reduce cardiovascular events.[4] ### Triglycerides ≥500 mg/dL Pancreatitis risk becomes increasingly important. Correct secondary drivers aggressively, especially uncontrolled diabetes and alcohol. Consider fibrate or prescription omega-3 therapy according to triglyceride level, kidney function, drug interactions, and local guidance. ### Triglycerides ≥1000 mg/dL This is a pancreatitis-prevention problem as well as an ASCVD problem. The 2026 US guideline emphasizes triglyceride-lowering therapy at this level, together with very-low-fat diet, alcohol elimination, and correction of secondary causes.[2,3] Fenofibrate is generally preferred over gemfibrozil when a fibrate must be combined with a statin because gemfibrozil increases statin-associated myopathy risk. Severe or recurrent chylomicronemia warrants specialist assessment for familial chylomicronemia syndrome or multifactorial chylomicronemia. ## Familial hypercholesterolemia Suspect heterozygous familial hypercholesterolemia when LDL-C is persistently very high, particularly ≥190 mg/dL, or when there is premature ASCVD, tendon xanthoma, or a strong family history. Diagnosis is clinical with optional genetic confirmation; a negative genetic test does not exclude polygenic or genetically unresolved disease. ### Practical approach - exclude secondary causes; - obtain a careful three-generation family history when feasible; - treat LDL-C early and intensively; - consider cascade screening of first-degree relatives; - refer severe, treatment-resistant, pediatric, or homozygous-suspected cases to a lipid specialist. Untreated homozygous familial hypercholesterolemia can produce extreme LDL-C elevation and childhood or young-adult ASCVD and requires specialist combination therapy. ## Elevated Lp(a) There is currently no approved therapy proven specifically to reduce cardiovascular events by lowering Lp(a) alone. Management therefore centers on: - more intensive LDL-C lowering when overall risk warrants; - aggressive treatment of smoking, blood pressure, diabetes, and other modifiable risk; - family screening in selected cases; - recognition that Lp(a) may help explain premature ASCVD despite otherwise acceptable standard lipids. PCSK9 inhibitors modestly lower Lp(a), but their approved role is primarily LDL-C lowering and ASCVD risk reduction. Dedicated Lp(a)-lowering outcome trials remain an active research area.[1-3] ## Special populations ### Diabetes Adults aged 40–75 years with diabetes generally warrant LDL-lowering therapy regardless of baseline LDL-C under the 2026 US guideline. Intensity depends on age, duration, additional risk factors, complications, and established ASCVD.[1-3] ### Chronic kidney disease Stage 3–4 CKD is a strong ASCVD risk state. Many adults aged 40–75 years with stage 3–4 CKD warrant LDL-lowering therapy regardless of baseline LDL-C. Dose selection and adverse-effect monitoring should account for kidney function.[1-3] ### HIV Adults aged 40–75 years with HIV are included among groups for whom LDL-lowering therapy is recommended in the 2026 US guideline. Review antiretroviral interactions carefully when selecting a statin.[1-3] ### Pregnancy, conception, and lactation Most lipid-lowering drugs are deferred during conception, pregnancy, and lactation unless a specialist determines that exceptional maternal risk justifies treatment. The 2026 guideline emphasizes individualized management, especially in severe familial hypercholesterolemia. Bile-acid sequestrants may be considered because they are not systemically absorbed, but tolerability and triglycerides must be considered.[1] ### Adults older than 75 years Decisions should consider life expectancy, frailty, polypharmacy, competing risk, prior treatment tolerance, ASCVD burden, and patient preferences. The 2026 guideline states that LDL-lowering pharmacotherapy can be considered after age 75 together with lifestyle intervention.[2,3] ## Follow-up and treatment escalation At each follow-up: - confirm adherence and access; - review lifestyle changes and secondary causes; - compare LDL-C, non-HDL-C, and triglycerides with the intended goal; - assess adverse effects and drug interactions; - intensify treatment when the residual LDL-C gap is clinically important; - avoid prolonged therapeutic inertia in very-high-risk patients. A practical escalation sequence is: ```text Define clinical risk and lipid phenotype ↓ Lifestyle + maximally tolerated statin when indicated ↓ Recheck response and adherence ↓ Goal achieved? ── yes → continue + periodic reassessment │ no ↓ Estimate LDL-C gap and urgency ↓ Add ezetimibe, bempedoic acid, or PCSK9-directed therapy based on required reduction, outcome evidence, tolerance, cost/access ↓ Reassess; combine therapies when needed ↓ Specialist referral for severe inherited disease, refractory values, or complex intolerance ``` ## Common pitfalls 1. Treating HDL-C as a pharmacologic target. Raising HDL-C numerically has not proved equivalent to reducing ASCVD events. 2. Using a short-term risk calculator in a patient with LDL-C ≥190 mg/dL and delaying treatment. 3. Failing to measure Lp(a) at least once in adulthood. 4. Assuming every muscle symptom represents permanent intolerance to all statins. 5. Leaving a very-high-risk ASCVD patient above LDL-C goal for months or years without intensification. 6. Ignoring triglycerides ≥1000 mg/dL, where pancreatitis prevention becomes urgent. 7. Using gemfibrozil casually with a statin despite increased myopathy risk. 8. Mixing risk categories and treatment thresholds from different jurisdictions without recognizing the difference. 9. Ordering repeated Lp(a) measurements without a clinical reason. 10. Focusing on LDL-C alone when severe hypertriglyceridemia, apoB discordance, or familial disease changes the clinical problem. ## Current guidance and evolving evidence ### Established care - statins remain first-line for most patients requiring LDL-C lowering; - explicit LDL-C/non-HDL-C goals are again part of US guidance; - PREVENT-ASCVD replaces the older Pooled Cohort Equations in the specified primary-prevention population; - Lp(a) should be measured at least once in adulthood; - CAC is a selective risk-reclassification tool; - high-risk and secondary-prevention patients often require combination therapy.[1-3] ### Evolving practice - earlier combination therapy is increasingly favored when a single agent is unlikely to reach goal; - apoB is increasingly used when LDL-C underestimates particle burden; - newer therapies are expanding options for statin-intolerant and genetically severe disease.[1,4,5] ### Investigational - dedicated Lp(a)-lowering therapies remain under outcome evaluation; - cardiovascular outcome evidence for inclisiran remains pending as of the evidence date.[1-3] ## References 1. Blumenthal RS, Morris PB, Gaudino M, et al. 2026 ACC/AHA/AACVPR/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Dyslipidemia. *Circulation.* 2026. doi:10.1161/CIR.0000000000001423. doi:10.1016/j.jacc.2025.11.016. https://professional.heart.org/en/science-news/2026-guideline-on-the-management-of-dyslipidemia 2. American Heart Association. Top Things to Know: 2026 Guideline on the Management of Dyslipidemia. Updated March 13, 2026. https://professional.heart.org/en/science-news/2026-guideline-on-the-management-of-dyslipidemia/top-things-to-know 3. American College of Cardiology. ACC/AHA Release New Clinical Guideline for Managing Dyslipidemia. March 13, 2026. https://www.acc.org/latest-in-cardiology/journal-scans/2026/03/13/15/20/acc-aha-release-new-clinical-guideline-for-managing-dyslipidemia 4. Mach F, Koskinas KC, Roeters van Lennep JE, et al. 2025 Focused Update of the 2019 ESC/EAS Guidelines for the management of dyslipidaemias. *European Heart Journal.* 2025. Official guideline hub: https://www.escardio.org/guidelines/clinical-practice-guidelines/all-esc-practice-guidelines/dyslipidaemias/ 5. European Society of Cardiology. 2025 Focused Update Dyslipidaemias: clinical messages and implementation resources. 2025. https://www.escardio.org/news/news-room/congress-news/2025-focused-update-dyslipidaemias/ 6. Cannon CP, Blazing MA, Giugliano RP, et al. Ezetimibe Added to Statin Therapy after Acute Coronary Syndromes. *N Engl J Med.* 2015;372:2387-2397. doi:10.1056/NEJMoa1410489. PMID:26039521. 7. Sabatine MS, Giugliano RP, Keech AC, et al. Evolocumab and Clinical Outcomes in Patients with Cardiovascular Disease. *N Engl J Med.* 2017;376:1713-1722. doi:10.1056/NEJMoa1615664. PMID:28304224. 8. Schwartz GG, Steg PG, Szarek M, et al. Alirocumab and Cardiovascular Outcomes after Acute Coronary Syndrome. *N Engl J Med.* 2018;379:2097-2107. doi:10.1056/NEJMoa1801174. PMID:30403574. 9. Nissen SE, Lincoff AM, Brennan D, et al. Bempedoic Acid and Cardiovascular Outcomes in Statin-Intolerant Patients. *N Engl J Med.* 2023;388:1353-1364. doi:10.1056/NEJMoa2215024. PMID:36876740. 10. Bhatt DL, Steg PG, Miller M, et al. Cardiovascular Risk Reduction with Icosapent Ethyl for Hypertriglyceridemia. *N Engl J Med.* 2019;380:11-22. doi:10.1056/NEJMoa1812792. PMID:30415628. 11. American College of Cardiology. Lipid Manager: Intensities of Statin Therapy. Updated 2026. https://tools.acc.org/ldl/ 12. American College of Cardiology. Getting to Goals: Applying the 2026 Dyslipidemia Guideline in High-Risk Patients. 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