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:T5968,## Summary Atrial fibrillation (AF) is a supraventricular tachyarrhythmia with disorganized atrial activation and ineffective atrial contraction. Diagnosis requires reviewable electrocardiographic evidence; pulse irregularity, photoplethysmography, or a wearable alert should trigger rhythm confirmation rather than serve as the final diagnosis.[1,2] Management has four simultaneous priorities: **stabilize hemodynamic compromise, prevent thromboembolism, control symptoms with rate and/or rhythm strategies, and treat the cardiovascular/systemic substrate that drives AF**.[1,2] AF-related instability—shock, critical hypotension, active ischemia, or acute pulmonary edema—requires immediate synchronized electrical cardioversion. Do not delay life-saving cardioversion solely to complete an anticoagulation work-up.[1,2] Stroke prevention depends on thromboembolic risk, not simply whether sinus rhythm is restored. The 2023 US guideline recommends oral anticoagulation when estimated annual thromboembolic risk is **≥2%** and considers it reasonable at **1% to <2%**.[1] The 2024 European guideline uses **CHA₂DS₂-VA** as its principal score, recommends oral anticoagulation at **≥2**, and considers it at **1**.[2] Direct oral anticoagulants are preferred over warfarin for most eligible patients, except those with a mechanical heart valve or clinically important rheumatic mitral stenosis, where a vitamin K antagonist remains standard.[1,2] Cardioversion anticoagulation thresholds differ. In the 2024 European pathway, when AF duration is **>24 hours**, elective cardioversion generally requires at least 3 weeks of effective anticoagulation or imaging to exclude atrial thrombus. The 2023 US guideline retains **≥48 hours or unknown duration** for its strongest pre-cardioversion anticoagulation/imaging recommendation. Both require individualized assessment because embolic risk is continuous and reported onset may be inaccurate.[1,2] Rate control is appropriate for many patients, but rhythm control should be discussed early when AF is symptomatic, recently diagnosed, difficult to rate-control, associated with heart failure or arrhythmia-induced cardiomyopathy, or when maintaining sinus rhythm is a major clinical goal. Catheter ablation is an established first-line rhythm-control option in selected symptomatic patients and has particularly strong value when AF contributes to heart failure with reduced ejection fraction.[1,2] > **Clinical pearl:** A successful cardioversion or ablation does not erase the substrate for stroke. Continue or stop long-term anticoagulation according to thromboembolic risk and the clinical indication, not a single sinus-rhythm tracing. ## ECG diagnosis Typical findings are: - irregularly irregular RR intervals when atrioventricular conduction is intact; - no consistent organized P waves; - fibrillatory atrial activity; - usually narrow QRS complexes unless bundle-branch block, ventricular pacing, rate-related aberrancy, or pre-excitation is present. A regular ventricular rhythm should prompt reconsideration, including atrial flutter with fixed conduction, paced rhythm, junctional rhythm, or AF with complete atrioventricular block. ### Device-detected atrial high-rate episodes Implanted devices and wearables can detect short atrial tachyarrhythmias that do not always carry the same risk as clinically established AF. Confirm the stored rhythm and episode duration before committing to long-term therapy. The 2023 US guideline supports a duration- and risk-based approach rather than automatic anticoagulation for every brief device alert.[1] ## Clinical classification | Pattern | Definition | Clinical use | |---|---|---| | First-diagnosed AF | First documented episode | Does not predict future burden | | Paroxysmal AF | Terminates spontaneously or with intervention within 7 days | Often suitable for early rhythm control | | Persistent AF | Continuous AF >7 days | Cardioversion or another rhythm strategy commonly needed | | Long-standing persistent AF | Continuous AF >12 months when rhythm control is still pursued | More advanced atrial remodeling; lower rhythm-maintenance success | | Permanent AF | Patient and clinician decide not to pursue further rhythm restoration | Management decision, not a distinct irreversible rhythm mechanism | AF burden, symptom burden, ventricular response, structural disease, and thromboembolic risk are more clinically informative than the temporal label alone. ## Pathophysiology AF usually requires a trigger and a susceptible atrial substrate. Pulmonary-vein ectopy is a major initiating mechanism. Atrial stretch, fibrosis, conduction heterogeneity, altered calcium handling, inflammation, adiposity, autonomic influences, and genetic susceptibility facilitate maintenance of the arrhythmia. Important substrate drivers include: - hypertension; - heart failure; - coronary artery disease; - valvular disease; - obesity; - obstructive sleep apnea; - diabetes; - chronic kidney disease; - hyperthyroidism; - alcohol excess; - chronic lung disease and hypoxemia; - cardiomyopathy and congenital heart disease. AF itself promotes electrical and structural remodeling, making recurrent AF more likely. ## Clinical presentation AF may be asymptomatic or cause: - palpitations; - dyspnea; - exercise intolerance; - fatigue; - chest discomfort; - dizziness or presyncope; - syncope with very rapid or very slow ventricular response; - worsening heart failure; - stroke or systemic embolism; - reduced functional capacity without prominent palpitations. ### Dangerous presentations Escalate immediately for: - shock or severe hypotension attributed to AF; - acute pulmonary edema; - ongoing myocardial ischemia; - altered consciousness from hypoperfusion; - pre-excited AF with a very rapid irregular wide-complex rhythm; - acute focal neurologic deficit; - severe bradycardia or prolonged pauses; - suspected acute coronary syndrome, pulmonary embolism, myocarditis, or another immediately dangerous precipitant. ## Initial assessment Clarify: - symptom onset and whether the rhythm has been continuously abnormal; - prior AF episodes and prior spontaneous conversion; - prior cardioversion or ablation; - anticoagulant name, dose, adherence, last dose, and missed doses; - prior stroke, transient ischemic attack, systemic embolism, or major bleeding; - heart failure, cardiomyopathy, valve disease, coronary disease, or congenital heart disease; - infection, hypoxia, dehydration, alcohol, stimulants, recent surgery, or pulmonary-embolism symptoms; - kidney and liver function relevant to drug choice; - pregnancy when applicable; - sleep-apnea symptoms and major modifiable risk factors. Physical assessment should focus on perfusion, blood pressure, oxygenation, congestion, murmurs, focal neurologic deficits, infection, and volume status. ## Investigations ### 12-lead ECG Confirm AF and assess: - ventricular rate; - QRS width and morphology; - pre-excitation; - ischemic changes; - prior infarction patterns; - ventricular hypertrophy; - baseline QT interval before selected antiarrhythmics. ### Laboratory studies Tailor testing to the clinical setting. Common studies include: - CBC; - sodium, potassium, magnesium, bicarbonate, and renal function; - glucose; - thyroid-stimulating hormone in newly recognized AF or when thyroid disease is plausible; - liver tests when anticoagulant or antiarrhythmic selection depends on them; - troponin when acute coronary syndrome or clinically relevant myocardial injury is suspected. ### Echocardiography Transthoracic echocardiography usually assesses: - left-ventricular ejection fraction; - left-atrial size; - significant valve disease; - ventricular hypertrophy; - right-heart disease; - cardiomyopathy. Transesophageal imaging is used when exclusion of left-atrial/appendage thrombus will change cardioversion or procedural management. ### Ambulatory monitoring Use ambulatory ECG monitoring when AF is intermittent, symptom-rhythm correlation is uncertain, pauses are suspected, rate control needs assessment, or post-treatment AF burden matters. ## Acute management pathway ```text Confirmed AF ↓ Is AF causing hemodynamic instability? ├─ Yes → synchronized electrical cardioversion now │ + treat precipitant │ + anticoagulate as soon as safely feasible when indicated └─ No ↓ Assess rate, LV function, pre-excitation, AF duration, anticoagulation status, symptoms, and reversible triggers ↓ Pre-excitation? ├─ Yes → avoid AV-nodal blockers; use an accessory-pathway-safe rhythm strategy └─ No → rate control, rhythm control, or both ↓ Assess cardioversion thromboembolic protection + long-term stroke risk ↓ Plan risk-factor treatment and longitudinal rhythm strategy ``` ## Hemodynamically unstable AF When AF is the cause of shock, critical hypotension, active ischemia, or acute pulmonary edema, perform **synchronized electrical cardioversion immediately**.[1,2] Do not delay for elective anticoagulation timing rules. Begin anticoagulation as soon as clinically safe when indicated and treat the underlying trigger in parallel. A biphasic shock strategy using appropriate device-specific energy and rapid escalation if the first attempt fails is standard. Sedation is used when the patient can tolerate it without delaying urgent cardioversion. ## Rate control Rate control can relieve symptoms and prevent persistent tachycardia-mediated ventricular dysfunction. The target should be individualized to symptoms, ventricular function, exercise requirements, and comorbidity rather than based on one resting heart rate.[1,2] ### Common choices | Agent/class | Useful setting | Important limitations | |---|---|---| | Beta-blocker | Broad acute/chronic use; adrenergic states; ischemic disease; HFrEF | Bradycardia, hypotension; avoid aggressive initiation in shock/decompensated HF | | Diltiazem or verapamil | Rapid control when LVEF is preserved | Avoid in significant HFrEF; hypotension/bradycardia | | Digoxin | HFrEF, sedentary patients, or adjunct when BP limits other drugs | Slower effect during intense adrenergic drive; renal clearance; toxicity/interactions | | Amiodarone | Selected critically ill patients when standard agents are unsuitable | May cardiovert; major long-term organ toxicity and drug interactions | The 2024 European guideline limits diltiazem/verapamil to patients with LVEF >40%.[2] ### Pre-excited AF A very rapid, irregular, wide-complex tachycardia in a patient with an accessory pathway can deteriorate to ventricular fibrillation. **Avoid AV-nodal blockers**, including: - beta-blockers; - diltiazem; - verapamil; - digoxin; - adenosine. Stable patients require an accessory-pathway-safe rhythm strategy under monitored specialist care; unstable patients require immediate synchronized cardioversion.[1] ## Rhythm control Rhythm control includes: - electrical cardioversion; - pharmacologic cardioversion; - antiarrhythmic maintenance therapy; - catheter ablation; - selected surgical ablation. Factors favoring early rhythm control include: - recent AF diagnosis; - persistent symptoms despite adequate rate control; - AF-associated heart failure or LV dysfunction; - suspected arrhythmia-induced cardiomyopathy; - difficulty controlling ventricular rate; - younger age and fewer advanced substrate features; - strong preference for sinus rhythm.[1,2] The EAST-AFNET 4 trial supported an early rhythm-control strategy in selected patients with recently diagnosed AF and cardiovascular conditions, reducing a composite of cardiovascular outcomes compared with usual care.[3] ## Cardioversion: anticoagulation and imaging Cardioversion can embolize pre-existing atrial thrombus and is followed by transient atrial mechanical dysfunction. Timing therefore matters.[1,2] ### 2024 European approach When known AF duration is **>24 hours** and the patient has not had at least 3 weeks of effective anticoagulation, elective cardioversion is generally delayed or performed after transesophageal imaging excludes atrial thrombus.[2] Therapeutic anticoagulation is generally continued for at least 4 weeks after cardioversion, with longer treatment based on long-term stroke risk.[2] ### 2023 US approach For AF **≥48 hours or of unknown duration**, establish therapeutic anticoagulation for at least 3 weeks before elective cardioversion or obtain imaging that excludes intracardiac thrombus.[1] Continue therapeutic anticoagulation for at least 4 weeks afterward.[1] For AF reported to be <48 hours, risk is not uniform. Consider duration certainty, thromboembolic risk, prior AF burden, and clinical context rather than assuming the episode is safe merely because it appears recent.[1] > **Caution:** Do not combine the duration threshold from one jurisdiction with the remainder of another protocol without recognizing the difference. ## Long-term stroke prevention ### US risk framework The 2023 ACC/AHA/ACCP/HRS guideline recommends anticoagulation when estimated annual thromboembolic risk is **≥2%** and considers anticoagulation reasonable at **1% to <2%**.[1] CHA₂DS₂-VASc remains a commonly used tool: - heart failure/LV dysfunction — 1; - hypertension — 1; - age ≥75 years — 2; - diabetes — 1; - prior stroke/TIA/systemic embolism — 2; - vascular disease — 1; - age 65-74 years — 1; - female sex category — 1. ### European risk framework The 2024 ESC guideline uses **CHA₂DS₂-VA**, omitting sex category from the principal score. Oral anticoagulation is recommended at ≥2 and should be considered at 1.[2] ### Bleeding risk A bleeding-risk score is most useful for finding modifiable hazards rather than denying anticoagulation to a patient with substantial stroke risk. Address: - uncontrolled hypertension; - avoidable antiplatelet or NSAID use; - alcohol excess; - untreated gastrointestinal or genitourinary bleeding lesions; - renal/hepatic dysfunction affecting drug exposure; - falls risk where modifiable; - poor warfarin time in therapeutic range when a VKA is required.[1,2] ## Oral anticoagulant selection For eligible AF patients without a mechanical valve or clinically important rheumatic mitral stenosis, direct oral anticoagulants are preferred to warfarin.[1,2] Before prescribing, verify: - current creatinine and calculated renal function using the method required by the label; - age and body weight; - liver disease; - interacting P-glycoprotein/CYP3A4 drugs; - indication for concomitant antiplatelet therapy; - adherence likelihood; - prior bleeding. Do not reduce a direct oral anticoagulant dose merely because a patient is elderly or perceived as fragile unless the approved dose-reduction criteria are met. Off-label underdosing can reduce stroke protection without eliminating bleeding risk.[1,2] ### When warfarin remains appropriate Use a vitamin K antagonist for: - mechanical prosthetic heart valves; - rheumatic mitral stenosis where guideline-directed VKA therapy remains standard; - selected patients with severe renal impairment or drug interactions that preclude a direct oral agent; - patients in whom cost, adherence structure, or another indication favors warfarin. ## Left atrial appendage occlusion Percutaneous left atrial appendage occlusion can be considered in selected patients who have a clear indication for stroke prevention but a nonreversible contraindication to long-term oral anticoagulation, or in carefully selected patients with exceptionally high bleeding risk after shared decision-making.[1] It is not a routine replacement for anticoagulation in a patient who can safely take a direct oral anticoagulant. ## Antiarrhythmic drug selection Choice depends on structural heart disease, LV function, coronary disease, renal/hepatic function, baseline QT, conduction disease, drug interactions, and prior response.[1,2] General principles: - class Ic drugs such as flecainide/propafenone are avoided in significant structural heart disease or prior myocardial infarction; - sotalol and dofetilide require careful QT and renal assessment; - amiodarone is effective but reserved when safer options are unsuitable because cumulative thyroid, lung, liver, ocular, neurologic, and skin toxicity is substantial; - dronedarone is not used in permanent AF or in unstable/recently decompensated heart failure; - inpatient initiation requirements vary by drug and jurisdiction. A “pill-in-the-pocket” class Ic strategy can be used in selected patients only after safety and efficacy are demonstrated in a monitored setting and an atrioventricular-nodal blocker is appropriately paired to prevent rapid atrial-flutter conduction.[1] ## Catheter ablation Catheter ablation is an established rhythm-control therapy. Pulmonary-vein isolation is the core lesion set for most AF ablation procedures.[1,2] Consider ablation when: - symptomatic AF persists despite an antiarrhythmic drug; - a patient prefers ablation over long-term drug therapy and is an appropriate candidate; - paroxysmal or selected persistent AF is newly treated and first-line ablation offers a favorable benefit-risk profile; - AF contributes to HFrEF or arrhythmia-induced cardiomyopathy.[1,2] Ablation reduces AF burden and improves symptoms, but recurrence can occur. Anticoagulation after ablation follows thromboembolic risk and periprocedural protocol rather than presumed procedural cure. ## AF with heart failure AF can be cause, consequence, or amplifier of heart failure. Suspect arrhythmia-induced cardiomyopathy when: - systolic dysfunction is new; - AF burden or ventricular rate is high; - another cause is not convincing; - ventricular function improves substantially after rhythm or rate control. In appropriate patients with HFrEF, catheter ablation can improve rhythm control and clinical outcomes. The CASTLE-AF trial demonstrated reduced death or heart-failure hospitalization in selected patients with symptomatic AF, HFrEF, and implanted rhythm devices.[4] See [Heart Failure With Reduced Ejection Fraction](heart-failure-with-reduced-ejection-fraction.md). ## AF with valvular disease Mitral stenosis, mitral regurgitation, and aortic valve disease can promote AF through atrial pressure/volume loading. Important distinction: - **mechanical valve or clinically important rheumatic mitral stenosis:** VKA-based anticoagulation; - other native valve lesions or bioprostheses: direct oral anticoagulants may be appropriate according to timing, indication, and guideline/label criteria.[1,2] See [Mitral Stenosis in Adults](mitral-stenosis-in-adults.md) and [Mitral Regurgitation in Adults](mitral-regurgitation-in-adults.md). ## AF associated with acute illness AF during sepsis, surgery, pulmonary disease, thyrotoxicosis, or another acute stressor is not automatically a one-time benign event. Treat the precipitant and control the ventricular response, but reassess after recovery for: - recurrent AF; - long-term stroke risk; - need for anticoagulation; - structural heart disease. The optimal anticoagulation approach during critical illness is individualized because acute bleeding and procedural risks may be high.[1] ## Lifestyle and substrate treatment Treating AF substrate improves rhythm-control success and general cardiovascular outcomes.[1,2] Key interventions include: - sustained weight reduction when overweight/obese; - regular aerobic activity appropriate to the patient; - blood-pressure control; - treatment of sleep apnea when clinically indicated; - diabetes management; - smoking cessation; - avoidance of binge alcohol and reduction of regular excess intake; - management of heart failure and coronary disease. Excess endurance training can promote AF in a subset of highly trained athletes; counseling should be individualized rather than discouraging normal physical activity. ## Follow-up and monitoring Reassess periodically because AF risk changes over time. Track: - symptom burden and functional capacity; - resting and exertional ventricular rate when relevant; - AF recurrence/burden; - anticoagulant adherence and renal/hepatic function; - bleeding events and modifiable bleeding risks; - antiarrhythmic toxicity; - blood pressure, weight, sleep apnea, alcohol exposure, and other substrate factors; - LV function when cardiomyopathy is present or suspected. ### Recheck sooner when - syncope or near-syncope occurs; - heart-failure symptoms worsen; - resting rate is persistently rapid despite treatment; - significant bleeding occurs; - kidney function changes enough to affect anticoagulant dosing; - antiarrhythmic toxicity is suspected; - new neurologic symptoms occur. ## Disposition ### Hospital care is generally appropriate for - hemodynamic instability; - acute pulmonary edema; - active ischemia; - pre-excited AF; - difficult rate control with organ dysfunction; - initiation of a therapy requiring monitored inpatient loading; - acute stroke or systemic embolism; - major bleeding while anticoagulated; - severe electrolyte disturbance or another dangerous precipitant. ### Outpatient management is often reasonable when - the patient is stable; - ventricular rate is acceptable; - there is no acute heart failure or ischemia; - stroke-prevention and cardioversion plans are clear; - follow-up is reliable. ## Complications Major complications include: - ischemic stroke and systemic embolism; - heart failure; - arrhythmia-induced cardiomyopathy; - hospitalization and reduced exercise capacity; - bleeding from antithrombotic therapy; - bradycardia or pauses related to intrinsic conduction disease or treatment; - antiarrhythmic drug toxicity; - recurrence after cardioversion or ablation. ## 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. PMID: 38033089. DOI: 10.1161/CIR.0000000000001193. https://pubmed.ncbi.nlm.nih.gov/38033089/ 2. Van Gelder IC, Rienstra M, Bunting KV, et al. 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://academic.oup.com/eurheartj/article/45/36/3314/7738779 3. Kirchhof P, Camm AJ, Goette A, et al. Early Rhythm-Control Therapy in Patients with Atrial Fibrillation. *N Engl J Med*. 2020;383:1305-1316. PMID: 32865375. DOI: 10.1056/NEJMoa2019422. https://pubmed.ncbi.nlm.nih.gov/32865375/ 4. Marrouche NF, Brachmann J, Andresen D, et al. Catheter Ablation for Atrial Fibrillation with Heart Failure. *N Engl J Med*. 2018;378:417-427. PMID: 29385358. DOI: 10.1056/NEJMoa1707855. https://pubmed.ncbi.nlm.nih.gov/29385358/19:T598c,## Summary Atrial fibrillation (AF) is a supraventricular tachyarrhythmia with disorganized atrial activation and ineffective atrial contraction. Diagnosis requires reviewable electrocardiographic evidence; pulse irregularity, photoplethysmography, or a wearable alert should trigger rhythm confirmation rather than serve as the final diagnosis.[1,2] Management has four simultaneous priorities: **stabilize hemodynamic compromise, prevent thromboembolism, control symptoms with rate and/or rhythm strategies, and treat the cardiovascular/systemic substrate that drives AF**.[1,2] AF-related instability—shock, critical hypotension, active ischemia, or acute pulmonary edema—requires immediate synchronized electrical cardioversion. Do not delay life-saving cardioversion solely to complete an anticoagulation work-up.[1,2] Stroke prevention depends on thromboembolic risk, not simply whether sinus rhythm is restored. The 2023 US guideline recommends oral anticoagulation when estimated annual thromboembolic risk is **≥2%** and considers it reasonable at **1% to <2%**.[1] The 2024 European guideline uses **CHA₂DS₂-VA** as its principal score, recommends oral anticoagulation at **≥2**, and considers it at **1**.[2] Direct oral anticoagulants are preferred over warfarin for most eligible patients, except those with a mechanical heart valve or clinically important rheumatic mitral stenosis, where a vitamin K antagonist remains standard.[1,2] Cardioversion anticoagulation thresholds differ. In the 2024 European pathway, when AF duration is **>24 hours**, elective cardioversion generally requires at least 3 weeks of effective anticoagulation or imaging to exclude atrial thrombus. The 2023 US guideline retains **≥48 hours or unknown duration** for its strongest pre-cardioversion anticoagulation/imaging recommendation. Both require individualized assessment because embolic risk is continuous and reported onset may be inaccurate.[1,2] Rate control is appropriate for many patients, but rhythm control should be discussed early when AF is symptomatic, recently diagnosed, difficult to rate-control, associated with heart failure or arrhythmia-induced cardiomyopathy, or when maintaining sinus rhythm is a major clinical goal. Catheter ablation is an established first-line rhythm-control option in selected symptomatic patients and has particularly strong value when AF contributes to heart failure with reduced ejection fraction.[1,2] > **Clinical pearl:** A successful cardioversion or ablation does not erase the substrate for stroke. Continue or stop long-term anticoagulation according to thromboembolic risk and the clinical indication, not a single sinus-rhythm tracing. ## ECG diagnosis Typical findings are: - irregularly irregular RR intervals when atrioventricular conduction is intact; - no consistent organized P waves; - fibrillatory atrial activity; - usually narrow QRS complexes unless bundle-branch block, ventricular pacing, rate-related aberrancy, or pre-excitation is present. A regular ventricular rhythm should prompt reconsideration, including atrial flutter with fixed conduction, paced rhythm, junctional rhythm, or AF with complete atrioventricular block. ### Device-detected atrial high-rate episodes Implanted devices and wearables can detect short atrial tachyarrhythmias that do not always carry the same risk as clinically established AF. Confirm the stored rhythm and episode duration before committing to long-term therapy. The 2023 US guideline supports a duration- and risk-based approach rather than automatic anticoagulation for every brief device alert.[1] ## Clinical classification | Pattern | Definition | Clinical use | |---|---|---| | First-diagnosed AF | First documented episode | Does not predict future burden | | Paroxysmal AF | Terminates spontaneously or with intervention within 7 days | Often suitable for early rhythm control | | Persistent AF | Continuous AF >7 days | Cardioversion or another rhythm strategy commonly needed | | Long-standing persistent AF | Continuous AF >12 months when rhythm control is still pursued | More advanced atrial remodeling; lower rhythm-maintenance success | | Permanent AF | Patient and clinician decide not to pursue further rhythm restoration | Management decision, not a distinct irreversible rhythm mechanism | AF burden, symptom burden, ventricular response, structural disease, and thromboembolic risk are more clinically informative than the temporal label alone. ## Pathophysiology AF usually requires a trigger and a susceptible atrial substrate. Pulmonary-vein ectopy is a major initiating mechanism. Atrial stretch, fibrosis, conduction heterogeneity, altered calcium handling, inflammation, adiposity, autonomic influences, and genetic susceptibility facilitate maintenance of the arrhythmia. Important substrate drivers include: - hypertension; - heart failure; - coronary artery disease; - valvular disease; - obesity; - obstructive sleep apnea; - diabetes; - chronic kidney disease; - hyperthyroidism; - alcohol excess; - chronic lung disease and hypoxemia; - cardiomyopathy and congenital heart disease. AF itself promotes electrical and structural remodeling, making recurrent AF more likely. ## Clinical presentation AF may be asymptomatic or cause: - palpitations; - dyspnea; - exercise intolerance; - fatigue; - chest discomfort; - dizziness or presyncope; - syncope with very rapid or very slow ventricular response; - worsening heart failure; - stroke or systemic embolism; - reduced functional capacity without prominent palpitations. ### Dangerous presentations Escalate immediately for: - shock or severe hypotension attributed to AF; - acute pulmonary edema; - ongoing myocardial ischemia; - altered consciousness from hypoperfusion; - pre-excited AF with a very rapid irregular wide-complex rhythm; - acute focal neurologic deficit; - severe bradycardia or prolonged pauses; - suspected [acute coronary syndrome](/library/acute-coronary-syndrome), pulmonary embolism, myocarditis, or another immediately dangerous precipitant. ## Initial assessment Clarify: - symptom onset and whether the rhythm has been continuously abnormal; - prior AF episodes and prior spontaneous conversion; - prior cardioversion or ablation; - anticoagulant name, dose, adherence, last dose, and missed doses; - prior stroke, transient ischemic attack, systemic embolism, or major bleeding; - heart failure, cardiomyopathy, valve disease, coronary disease, or congenital heart disease; - infection, hypoxia, dehydration, alcohol, stimulants, recent surgery, or pulmonary-embolism symptoms; - kidney and liver function relevant to drug choice; - pregnancy when applicable; - sleep-apnea symptoms and major modifiable risk factors. Physical assessment should focus on perfusion, blood pressure, oxygenation, congestion, murmurs, focal neurologic deficits, infection, and volume status. ## Investigations ### 12-lead ECG Confirm AF and assess: - ventricular rate; - QRS width and morphology; - pre-excitation; - ischemic changes; - prior infarction patterns; - ventricular hypertrophy; - baseline QT interval before selected antiarrhythmics. ### Laboratory studies Tailor testing to the clinical setting. Common studies include: - CBC; - sodium, potassium, magnesium, bicarbonate, and renal function; - glucose; - thyroid-stimulating hormone in newly recognized AF or when thyroid disease is plausible; - liver tests when anticoagulant or antiarrhythmic selection depends on them; - troponin when acute coronary syndrome or clinically relevant myocardial injury is suspected. ### Echocardiography Transthoracic echocardiography usually assesses: - left-ventricular ejection fraction; - left-atrial size; - significant valve disease; - ventricular hypertrophy; - right-heart disease; - cardiomyopathy. Transesophageal imaging is used when exclusion of left-atrial/appendage thrombus will change cardioversion or procedural management. ### Ambulatory monitoring Use ambulatory ECG monitoring when AF is intermittent, symptom-rhythm correlation is uncertain, pauses are suspected, rate control needs assessment, or post-treatment AF burden matters. ## Acute management pathway ```text Confirmed AF ↓ Is AF causing hemodynamic instability? ├─ Yes → synchronized electrical cardioversion now │ + treat precipitant │ + anticoagulate as soon as safely feasible when indicated └─ No ↓ Assess rate, LV function, pre-excitation, AF duration, anticoagulation status, symptoms, and reversible triggers ↓ Pre-excitation? ├─ Yes → avoid AV-nodal blockers; use an accessory-pathway-safe rhythm strategy └─ No → rate control, rhythm control, or both ↓ Assess cardioversion thromboembolic protection + long-term stroke risk ↓ Plan risk-factor treatment and longitudinal rhythm strategy ``` ## Hemodynamically unstable AF When AF is the cause of shock, critical hypotension, active ischemia, or acute pulmonary edema, perform **synchronized electrical cardioversion immediately**.[1,2] Do not delay for elective anticoagulation timing rules. Begin anticoagulation as soon as clinically safe when indicated and treat the underlying trigger in parallel. A biphasic shock strategy using appropriate device-specific energy and rapid escalation if the first attempt fails is standard. Sedation is used when the patient can tolerate it without delaying urgent cardioversion. ## Rate control Rate control can relieve symptoms and prevent persistent tachycardia-mediated ventricular dysfunction. The target should be individualized to symptoms, ventricular function, exercise requirements, and comorbidity rather than based on one resting heart rate.[1,2] ### Common choices | Agent/class | Useful setting | Important limitations | |---|---|---| | Beta-blocker | Broad acute/chronic use; adrenergic states; ischemic disease; HFrEF | Bradycardia, hypotension; avoid aggressive initiation in shock/decompensated HF | | Diltiazem or verapamil | Rapid control when LVEF is preserved | Avoid in significant HFrEF; hypotension/bradycardia | | Digoxin | HFrEF, sedentary patients, or adjunct when BP limits other drugs | Slower effect during intense adrenergic drive; renal clearance; toxicity/interactions | | Amiodarone | Selected critically ill patients when standard agents are unsuitable | May cardiovert; major long-term organ toxicity and drug interactions | The 2024 European guideline limits diltiazem/verapamil to patients with LVEF >40%.[2] ### Pre-excited AF A very rapid, irregular, wide-complex tachycardia in a patient with an accessory pathway can deteriorate to ventricular fibrillation. **Avoid AV-nodal blockers**, including: - beta-blockers; - diltiazem; - verapamil; - digoxin; - adenosine. Stable patients require an accessory-pathway-safe rhythm strategy under monitored specialist care; unstable patients require immediate synchronized cardioversion.[1] ## Rhythm control Rhythm control includes: - electrical cardioversion; - pharmacologic cardioversion; - antiarrhythmic maintenance therapy; - catheter ablation; - selected surgical ablation. Factors favoring early rhythm control include: - recent AF diagnosis; - persistent symptoms despite adequate rate control; - AF-associated heart failure or LV dysfunction; - suspected arrhythmia-induced cardiomyopathy; - difficulty controlling ventricular rate; - younger age and fewer advanced substrate features; - strong preference for sinus rhythm.[1,2] The EAST-AFNET 4 trial supported an early rhythm-control strategy in selected patients with recently diagnosed AF and cardiovascular conditions, reducing a composite of cardiovascular outcomes compared with usual care.[3] ## Cardioversion: anticoagulation and imaging Cardioversion can embolize pre-existing atrial thrombus and is followed by transient atrial mechanical dysfunction. Timing therefore matters.[1,2] ### 2024 European approach When known AF duration is **>24 hours** and the patient has not had at least 3 weeks of effective anticoagulation, elective cardioversion is generally delayed or performed after transesophageal imaging excludes atrial thrombus.[2] Therapeutic anticoagulation is generally continued for at least 4 weeks after cardioversion, with longer treatment based on long-term stroke risk.[2] ### 2023 US approach For AF **≥48 hours or of unknown duration**, establish therapeutic anticoagulation for at least 3 weeks before elective cardioversion or obtain imaging that excludes intracardiac thrombus.[1] Continue therapeutic anticoagulation for at least 4 weeks afterward.[1] For AF reported to be <48 hours, risk is not uniform. Consider duration certainty, thromboembolic risk, prior AF burden, and clinical context rather than assuming the episode is safe merely because it appears recent.[1] > **Caution:** Do not combine the duration threshold from one jurisdiction with the remainder of another protocol without recognizing the difference. ## Long-term stroke prevention ### US risk framework The 2023 ACC/AHA/ACCP/HRS guideline recommends anticoagulation when estimated annual thromboembolic risk is **≥2%** and considers anticoagulation reasonable at **1% to <2%**.[1] CHA₂DS₂-VASc remains a commonly used tool: - heart failure/LV dysfunction — 1; - hypertension — 1; - age ≥75 years — 2; - diabetes — 1; - prior stroke/TIA/systemic embolism — 2; - vascular disease — 1; - age 65-74 years — 1; - female sex category — 1. ### European risk framework The 2024 ESC guideline uses **CHA₂DS₂-VA**, omitting sex category from the principal score. Oral anticoagulation is recommended at ≥2 and should be considered at 1.[2] ### Bleeding risk A bleeding-risk score is most useful for finding modifiable hazards rather than denying anticoagulation to a patient with substantial stroke risk. Address: - uncontrolled hypertension; - avoidable antiplatelet or NSAID use; - alcohol excess; - untreated gastrointestinal or genitourinary bleeding lesions; - renal/hepatic dysfunction affecting drug exposure; - falls risk where modifiable; - poor warfarin time in therapeutic range when a VKA is required.[1,2] ## Oral anticoagulant selection For eligible AF patients without a mechanical valve or clinically important rheumatic mitral stenosis, direct oral anticoagulants are preferred to warfarin.[1,2] Before prescribing, verify: - current creatinine and calculated renal function using the method required by the label; - age and body weight; - liver disease; - interacting P-glycoprotein/CYP3A4 drugs; - indication for concomitant antiplatelet therapy; - adherence likelihood; - prior bleeding. Do not reduce a direct oral anticoagulant dose merely because a patient is elderly or perceived as fragile unless the approved dose-reduction criteria are met. Off-label underdosing can reduce stroke protection without eliminating bleeding risk.[1,2] ### When warfarin remains appropriate Use a vitamin K antagonist for: - mechanical prosthetic heart valves; - rheumatic mitral stenosis where guideline-directed VKA therapy remains standard; - selected patients with severe renal impairment or drug interactions that preclude a direct oral agent; - patients in whom cost, adherence structure, or another indication favors warfarin. ## Left atrial appendage occlusion Percutaneous left atrial appendage occlusion can be considered in selected patients who have a clear indication for stroke prevention but a nonreversible contraindication to long-term oral anticoagulation, or in carefully selected patients with exceptionally high bleeding risk after shared decision-making.[1] It is not a routine replacement for anticoagulation in a patient who can safely take a direct oral anticoagulant. ## Antiarrhythmic drug selection Choice depends on structural heart disease, LV function, coronary disease, renal/hepatic function, baseline QT, conduction disease, drug interactions, and prior response.[1,2] General principles: - class Ic drugs such as flecainide/propafenone are avoided in significant structural heart disease or prior myocardial infarction; - sotalol and dofetilide require careful QT and renal assessment; - amiodarone is effective but reserved when safer options are unsuitable because cumulative thyroid, lung, liver, ocular, neurologic, and skin toxicity is substantial; - dronedarone is not used in permanent AF or in unstable/recently decompensated heart failure; - inpatient initiation requirements vary by drug and jurisdiction. A “pill-in-the-pocket” class Ic strategy can be used in selected patients only after safety and efficacy are demonstrated in a monitored setting and an atrioventricular-nodal blocker is appropriately paired to prevent rapid atrial-flutter conduction.[1] ## Catheter ablation Catheter ablation is an established rhythm-control therapy. Pulmonary-vein isolation is the core lesion set for most AF ablation procedures.[1,2] Consider ablation when: - symptomatic AF persists despite an antiarrhythmic drug; - a patient prefers ablation over long-term drug therapy and is an appropriate candidate; - paroxysmal or selected persistent AF is newly treated and first-line ablation offers a favorable benefit-risk profile; - AF contributes to HFrEF or arrhythmia-induced cardiomyopathy.[1,2] Ablation reduces AF burden and improves symptoms, but recurrence can occur. Anticoagulation after ablation follows thromboembolic risk and periprocedural protocol rather than presumed procedural cure. ## AF with heart failure AF can be cause, consequence, or amplifier of heart failure. Suspect arrhythmia-induced cardiomyopathy when: - systolic dysfunction is new; - AF burden or ventricular rate is high; - another cause is not convincing; - ventricular function improves substantially after rhythm or rate control. In appropriate patients with HFrEF, catheter ablation can improve rhythm control and clinical outcomes. The CASTLE-AF trial demonstrated reduced death or heart-failure hospitalization in selected patients with symptomatic AF, HFrEF, and implanted rhythm devices.[4] See [Heart Failure With Reduced Ejection Fraction](heart-failure-with-reduced-ejection-fraction.md). ## AF with valvular disease Mitral stenosis, mitral regurgitation, and aortic valve disease can promote AF through atrial pressure/volume loading. Important distinction: - **mechanical valve or clinically important rheumatic mitral stenosis:** VKA-based anticoagulation; - other native valve lesions or bioprostheses: direct oral anticoagulants may be appropriate according to timing, indication, and guideline/label criteria.[1,2] See [Mitral Stenosis in Adults](mitral-stenosis-in-adults.md) and [Mitral Regurgitation in Adults](mitral-regurgitation-in-adults.md). ## AF associated with acute illness AF during sepsis, surgery, pulmonary disease, thyrotoxicosis, or another acute stressor is not automatically a one-time benign event. Treat the precipitant and control the ventricular response, but reassess after recovery for: - recurrent AF; - long-term stroke risk; - need for anticoagulation; - structural heart disease. The optimal anticoagulation approach during critical illness is individualized because acute bleeding and procedural risks may be high.[1] ## Lifestyle and substrate treatment Treating AF substrate improves rhythm-control success and general cardiovascular outcomes.[1,2] Key interventions include: - sustained weight reduction when overweight/obese; - regular aerobic activity appropriate to the patient; - blood-pressure control; - treatment of sleep apnea when clinically indicated; - diabetes management; - smoking cessation; - avoidance of binge alcohol and reduction of regular excess intake; - management of heart failure and coronary disease. Excess endurance training can promote AF in a subset of highly trained athletes; counseling should be individualized rather than discouraging normal physical activity. ## Follow-up and monitoring Reassess periodically because AF risk changes over time. Track: - symptom burden and functional capacity; - resting and exertional ventricular rate when relevant; - AF recurrence/burden; - anticoagulant adherence and renal/hepatic function; - bleeding events and modifiable bleeding risks; - antiarrhythmic toxicity; - blood pressure, weight, sleep apnea, alcohol exposure, and other substrate factors; - LV function when cardiomyopathy is present or suspected. ### Recheck sooner when - syncope or near-syncope occurs; - heart-failure symptoms worsen; - resting rate is persistently rapid despite treatment; - significant bleeding occurs; - kidney function changes enough to affect anticoagulant dosing; - antiarrhythmic toxicity is suspected; - new neurologic symptoms occur. ## Disposition ### Hospital care is generally appropriate for - hemodynamic instability; - acute pulmonary edema; - active ischemia; - pre-excited AF; - difficult rate control with organ dysfunction; - initiation of a therapy requiring monitored inpatient loading; - acute stroke or systemic embolism; - major bleeding while anticoagulated; - severe electrolyte disturbance or another dangerous precipitant. ### Outpatient management is often reasonable when - the patient is stable; - ventricular rate is acceptable; - there is no acute heart failure or ischemia; - stroke-prevention and cardioversion plans are clear; - follow-up is reliable. ## Complications Major complications include: - ischemic stroke and systemic embolism; - heart failure; - arrhythmia-induced cardiomyopathy; - hospitalization and reduced exercise capacity; - bleeding from antithrombotic therapy; - bradycardia or pauses related to intrinsic conduction disease or treatment; - antiarrhythmic drug toxicity; - recurrence after cardioversion or ablation. ## 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. PMID: 38033089. DOI: 10.1161/CIR.0000000000001193. https://pubmed.ncbi.nlm.nih.gov/38033089/ 2. Van Gelder IC, Rienstra M, Bunting KV, et al. 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://academic.oup.com/eurheartj/article/45/36/3314/7738779 3. Kirchhof P, Camm AJ, Goette A, et al. Early Rhythm-Control Therapy in Patients with Atrial Fibrillation. *N Engl J Med*. 2020;383:1305-1316. PMID: 32865375. DOI: 10.1056/NEJMoa2019422. https://pubmed.ncbi.nlm.nih.gov/32865375/ 4. Marrouche NF, Brachmann J, Andresen D, et al. Catheter Ablation for Atrial Fibrillation with Heart Failure. *N Engl J Med*. 2018;378:417-427. PMID: 29385358. DOI: 10.1056/NEJMoa1707855. https://pubmed.ncbi.nlm.nih.gov/29385358/1a: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.1b: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.**1c: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. September 1, 2026. https://www.acc.org/Latest-in-Cardiology/Articles/2026/09/01/01/Feature-Getting-to-Goals1d:Tb3af,## One-minute summary **Acute kidney injury (AKI)** is an abrupt decline in kidney function identified by a rise in serum creatinine and/or reduced urine output. The current established international definition remains the **KDIGO 2012 definition**: an increase in serum creatinine by **≥0.3 mg/dL (≥26.5 µmol/L) within 48 hours**, an increase to **≥1.5 times baseline within 7 days**, or urine output **<0.5 mL/kg/hour for 6 hours**.[1] NICE uses equivalent criteria in UK practice.[2] AKI is a **syndrome, not a diagnosis**. Immediate priorities are to identify reversible threats, determine the cause, restore adequate perfusion when appropriate, relieve urinary obstruction, stop or adjust nephrotoxins and renally cleared drugs, manage electrolyte/acid-base/volume complications, and recognize patients who need urgent nephrology or kidney replacement therapy (KRT).[1,2] The classic “prerenal / intrinsic / postrenal” framework is useful, but many patients—especially those with sepsis, heart failure, cirrhosis, major surgery, or shock—have mixed mechanisms. A low fractional excretion of sodium or a bland urine sediment should never override the clinical picture. **Do not dialyze because the creatinine is high.** Initiate KRT urgently for life-threatening complications such as refractory hyperkalemia, severe acid-base disturbance, pulmonary edema/volume overload, or uremic complications; otherwise use the overall clinical trajectory rather than a single creatinine or BUN threshold.[1,6] **Current practice point (2026):** KDIGO has released a **2026 AKI/acute kidney disease (AKD) public-review draft**, but the final guideline has not yet replaced the 2012 standard. New draft concepts—biomarkers, risk models, AKD continuum, updated fluid and KRT guidance—should be considered **emerging until final publication**.[8] --- ## Core concepts ### What AKI represents physiologically Kidney function depends on adequate renal perfusion, intact glomerular filtration, functioning tubular/interstitial tissue, and unobstructed urine flow. AKI can arise from failure at any of these levels and often evolves through several mechanisms at once. A creatinine rise is a **delayed functional marker**: serum creatinine may not increase immediately after injury, and its concentration is influenced by muscle mass, fluid balance, creatinine production, medications that alter tubular secretion, and the baseline kidney reserve. Urine output can change earlier, but oliguria is neither perfectly sensitive nor specific for structural kidney injury.[1] The clinical objective is therefore not merely to “normalize creatinine.” It is to: 1. prevent ongoing injury; 2. preserve oxygen delivery and perfusion; 3. identify treatable causes; 4. prevent lethal electrolyte/volume/acid-base complications; 5. minimize avoidable drug toxicity; 6. recognize transition to persistent AKI/AKD and later CKD. --- ## Definition and KDIGO staging ### Diagnostic criteria AKI is present if **any** of the following occur:[1,2] - serum creatinine rises by **≥0.3 mg/dL (≥26.5 µmol/L) within 48 hours**; - serum creatinine rises to **≥1.5 × baseline**, known or presumed to have occurred within the prior 7 days; - urine output falls to **<0.5 mL/kg/hour for at least 6 hours**. #### KDIGO staging | Stage | Serum creatinine criterion | Urine-output criterion | |---|---|---| | **1** | 1.5–1.9 × baseline **or** rise ≥0.3 mg/dL (≥26.5 µmol/L) | <0.5 mL/kg/h for 6–12 h | | **2** | 2.0–2.9 × baseline | <0.5 mL/kg/h for ≥12 h | | **3** | 3.0 × baseline **or** creatinine ≥4.0 mg/dL (≥353.6 µmol/L) with an acute rise **or** initiation of KRT | <0.3 mL/kg/h for ≥24 h **or** anuria ≥12 h | **Board pearl:** Stage by the **worst criterion** met. A patient can be stage 3 by urine output even if the creatinine rise appears modest. #### Baseline creatinine problems Baseline creatinine may be unknown. Options include: - the most recent reliable pre-illness creatinine; - a stable outpatient value from the preceding months; - adjudication based on prior records and clinical context. Back-calculating a creatinine from an assumed normal eGFR can misclassify patients and should not be treated as a precise substitute for a known baseline. --- ## AKI, AKD, and CKD continuum AKI describes abrupt kidney dysfunction over **≤7 days**. The ADQI framework introduced **acute kidney disease (AKD)** for kidney disease persisting **7–90 days** after an acute initiating event; disease persisting beyond 90 days meets a chronic kidney disease time criterion.[4] This continuum matters because apparent “recovery” from creatinine-defined AKI does not eliminate future risk. AKI survivors have increased risk of recurrent AKI, CKD, cardiovascular events, and death. Post-discharge kidney follow-up is part of AKI care, not an optional afterthought.[1,4] --- ## Epidemiology and prognosis AKI is common across hospital medicine. A large meta-analysis using KDIGO-equivalent definitions found a pooled adult AKI incidence of about **21.6%** during hospital episodes and an associated mortality of about **23.9%**, although rates vary greatly by case mix, geography, and illness severity.[3] ICU cohorts are substantially higher risk; the ADQI consensus summarizes AKI rates around 50% in critical care populations.[4] Severity, duration, recurrence, multiorgan failure, and incomplete recovery all worsen prognosis. Stage 1 AKI is not benign, and repeated “small” creatinine rises can carry meaningful long-term risk. --- ## Risk factors Important risk factors include:[2] - pre-existing CKD, especially eGFR <60 mL/min/1.73 m²; - older age; - diabetes mellitus; - heart failure; - liver disease/cirrhosis; - previous AKI; - sepsis or systemic inflammatory illness; - hypovolemia or hemorrhage; - major or emergency surgery; - urinary tract obstruction or urologic disease; - nephrotoxins or drugs that worsen hemodynamics during acute illness; - recent iodinated contrast exposure in susceptible patients; - hematologic malignancy, tumor lysis, myeloma, or hemolysis/rhabdomyolysis in selected contexts. #### Common medication/exposure contributors | Exposure | Mechanism / concern | Practical response | |---|---|---| | NSAIDs | Afferent arteriolar vasoconstriction; interstitial nephritis | Stop when AKI suspected unless a compelling reason exists | | ACE inhibitor / ARB | Reduces efferent arteriolar tone; can worsen GFR in hypoperfusion, bilateral renal artery stenosis | Review/temporarily hold during significant hypovolemia, shock, vomiting/diarrhea or sepsis; reassess indication when stable | | Diuretics | Can aggravate effective volume depletion; useful for congestion | Do not reflexively stop if patient is markedly congested; treat the physiology | | Aminoglycosides | Tubular toxicity | Avoid if alternatives exist; therapeutic drug monitoring if required | | Vancomycin | AKI risk increases with excessive exposure and other nephrotoxins | Use current AUC/local monitoring strategy; reassess co-nephrotoxins | | Iodinated contrast | Risk is concentrated in selected high-risk patients; causal risk historically overestimated | Do not delay clinically important emergency imaging; use risk-based hydration strategy | | Calcineurin inhibitors | Vasoconstriction and chronic/acute toxicity | Check level/interactions; transplant-nephrology input | | Chemotherapy / targeted agents | Multiple mechanisms: TLS, TMA, interstitial nephritis, tubular injury | Drug-specific evaluation, oncology/nephrology collaboration | **Clinical trap:** “ACE inhibitor + diuretic + NSAID” can be particularly hazardous during dehydration because renal autoregulation and circulating volume are impaired simultaneously. --- ## Etiology: practical classification ### 1. Reduced renal perfusion / hemodynamic AKI Common causes: - hypovolemia: vomiting, diarrhea, hemorrhage, diuresis, burns; - distributive shock/sepsis; - cardiogenic shock or severe low-output heart failure; - advanced cirrhosis with low effective arterial volume; - medications that impair autoregulation in a susceptible patient; - renal artery compromise. Early hemodynamic AKI may be rapidly reversible, but persistent hypoperfusion can progress to tubular injury. ### 2. Intrinsic renal parenchymal injury #### Acute tubular injury (ATI) Common triggers: - ischemia/shock; - sepsis; - major surgery; - nephrotoxins; - pigments (myoglobin/hemoglobin); - prolonged hemodynamic insult. Urine sediment may show **granular “muddy brown” casts** and renal tubular epithelial cells, but their absence does not exclude ATI. #### Acute interstitial nephritis (AIN) Potential causes include: - antibiotics (e.g., beta-lactams, sulfonamides); - proton-pump inhibitors; - NSAIDs; - immune-checkpoint inhibitors; - infections and systemic disease. The classic triad of **fever, rash, eosinophilia** is uncommon; do not require it for diagnosis. #### Glomerular disease Think urgently about glomerulonephritis when AKI is accompanied by: - hematuria; - proteinuria; - red-cell casts/dysmorphic red cells; - hypertension/edema; - systemic inflammatory features (purpura, pulmonary hemorrhage, sinus disease, arthritis, low complement, etc.). #### Vascular causes - thrombotic microangiopathy; - malignant hypertension; - renal infarction/embolism; - atheroembolic disease; - renal vein thrombosis in selected settings. ### 3. Postrenal / obstructive AKI Causes include: - benign prostatic obstruction; - stones; - pelvic/retroperitoneal malignancy; - blood clots; - neurogenic bladder; - urethral obstruction; - bilateral ureteric obstruction; - obstruction of a solitary functioning kidney. Obstruction can occur **without hydronephrosis early** or in dehydration/retroperitoneal fibrosis, so imaging is not infallible. --- ## Initial clinical assessment ### Immediate questions 1. Is the patient unstable? 2. Is there severe hyperkalemia, pulmonary edema, severe acidosis, pericarditis/encephalopathy, or another KRT-level complication? 3. Is the patient volume depleted, congested, or in shock? 4. Could there be urinary obstruction? 5. Is there a nephrotoxin or recent medication change? 6. Does urine/clinical context suggest glomerulonephritis, interstitial nephritis, TMA, myeloma, rhabdomyolysis, or another intrinsic process? --- ## History Focus on: #### Volume and hemodynamic history - oral intake; - vomiting/diarrhea; - fever/sepsis symptoms; - bleeding; - diuretic escalation; - hypotension/syncope; - heart failure symptoms; - cirrhosis/ascites. #### Urinary history - reduced urine volume or anuria; - hesitancy, poor stream, retention; - flank pain/colic; - hematuria; - recent urologic procedure; - pelvic cancer. #### Drug/exposure history - NSAIDs, ACEi/ARB, diuretics; - antibiotics and recent hospitalization; - contrast exposure; - herbal/supplement use; - chemotherapy or immune-checkpoint therapy; - recreational drugs/toxins; - creatine supplements or drugs affecting creatinine secretion. #### Systemic clues - rash/purpura; - arthralgia; - hemoptysis; - sinus disease; - neuropathy; - fever; - weight loss; - muscle pain/immobility/seizure (rhabdomyolysis); - diarrhea followed by anemia/thrombocytopenia (TMA/HUS context). --- ## Examination Assess both **volume depletion and congestion**—they can coexist. #### General and hemodynamic - blood pressure and trend; - heart rate; - capillary refill/peripheral temperature; - mental status; - orthostatic features when safe and relevant. #### Volume status - mucous membranes; - jugular venous pressure; - peripheral edema; - lung crackles; - ascites; - daily weight trend; - bedside ultrasound where expertise exists. #### Cause-specific signs - bladder distention; - flank tenderness; - rash/purpura; - signs of endocarditis; - pulmonary hemorrhage; - severe hypertension with end-organ injury. **Pitfall:** JVP, IVC ultrasound, urine sodium, and physical signs each have limitations. Use converging evidence rather than one “volume status” variable. --- ## Diagnostic workup ### Minimum initial tests in most hospitalized AKI - repeat serum creatinine/urea; - sodium, potassium, bicarbonate; - calcium, phosphate, magnesium as appropriate; - CBC; - urinalysis/dipstick; - urine microscopy when intrinsic disease is possible; - glucose; - ECG if hyperkalemia or arrhythmia risk; - strict urine-output measurement when clinically important. NICE recommends urine dipstick for **blood, protein, leukocytes, nitrites, and glucose** as soon as AKI is suspected or detected.[2] ### Additional tests guided by context | Suspicion | Useful tests | |---|---| | Sepsis | cultures, lactate, source evaluation | | Rhabdomyolysis | CK, phosphate, calcium, urinalysis with heme but few/no RBCs | | Hemolysis/TMA | smear, LDH, haptoglobin, bilirubin, platelets, ADAMTS13 when indicated | | Glomerulonephritis | urine microscopy, urine protein quantification, C3/C4, ANA, ANCA, anti-GBM, hepatitis/HIV tests as context dictates | | Myeloma | serum free light chains, serum/urine electrophoresis/immunofixation | | AIN | medication timeline; eosinophils are nonspecific; biopsy if diagnosis will alter therapy | | Obstruction | bladder scan; renal tract ultrasound or CT depending on suspected level/cause | --- ## Urinalysis and urine microscopy Urine sediment can be one of the highest-yield bedside “kidney biopsies.” | Finding | Suggests | Caveat | |---|---|---| | Muddy brown granular casts / tubular epithelial cells | Acute tubular injury | Sensitivity varies; absence does not exclude ATI | | RBC casts / dysmorphic RBCs | Glomerulonephritis | Urgent nephrology workup | | WBC casts | Interstitial nephritis or pyelonephritis | Not specific | | Heavy proteinuria | Glomerular disease, paraprotein disease | Dipstick underdetects some light chains | | Heme-positive dipstick with few RBCs | Myoglobinuria/hemoglobinuria | Correlate with CK/hemolysis | | Crystals | Drug/crystal nephropathy, uric acid, oxalate | Context determines significance | NICE specifically advises considering acute nephritis and nephrology referral when AKI has no obvious cause and urinalysis shows **hematuria plus proteinuria** without UTI or catheter trauma.[2] --- ## Fractional excretion indices: use cautiously #### FeNa \[ FeNa(\%) = \frac{Urine\ Na \times Plasma\ Cr}{Plasma\ Na \times Urine\ Cr}\times 100 \] A low FeNa can occur in reduced effective circulating volume, but also in: - early sepsis; - contrast-associated AKI; - pigment nephropathy; - glomerulonephritis; - hepatorenal physiology; - some obstructive states. A high FeNa can occur with diuretics, CKD, or established tubular injury. #### FeUrea Sometimes used when diuretics confound FeNa, but FeUrea is also imperfect and should not be treated as a diagnostic truth test. **Board pearl:** The distinction between “prerenal azotemia” and “ATN” is not reliably made by one urine index. --- ## Imaging ### Renal tract ultrasound Use when obstruction is possible or the cause is unclear. NICE advises **immediate ultrasound (within 6 hours)** when pyonephrosis/infected obstruction is suspected.[2] Do not routinely order ultrasound if the cause is already clear and obstruction is not clinically plausible.[2] ### CT Useful when stone disease, retroperitoneal pathology, vascular disease, trauma, or another abdominal cause is suspected. **Do not withhold or delay emergency contrast imaging when delay is likely to be clinically harmful.** NICE’s 2024 update emphasizes that contrast-associated AKI risk is small but increased when eGFR is <30 mL/min/1.73 m² and specifically advises not delaying emergency iodinated contrast when the clinical cost of delay is significant.[2] --- ## Differential diagnosis by pattern | Pattern | Leading possibilities | Clues that shift probability | |---|---|---| | Oliguria after vomiting/diarrhea | Hypovolemia, ATI if prolonged | Orthostasis, low JVP, hemoconcentration, response to cautious fluid | | AKI + edema + pulmonary congestion | Cardiorenal syndrome, GN, renal failure with volume overload | JVP, BNP context, echo, urine sediment, proteinuria | | AKI + hematuria + proteinuria | GN, vasculitis, anti-GBM, infection-related GN | RBC casts, systemic features, complement/serologies | | AKI + thrombocytopenia + hemolysis | TMA/TTP/HUS, malignant HTN | Schistocytes, LDH, haptoglobin, BP, ADAMTS13 context | | AKI + very high CK | Rhabdomyolysis | Muscle injury, dark urine, heme-positive dipstick without RBCs | | AKI + eosinophilia/rash after new drug | AIN | Often lacks classic triad; biopsy may be needed | | AKI + anuria/retention | Obstruction until proven otherwise | Bladder scan, ultrasound/CT | | AKI in cirrhosis | Volume depletion, sepsis, ATI, hepatorenal syndrome, drugs | Diagnose HRS only after excluding/treating competing causes | --- ## Management: stepwise approach ### STEP 1 — Stabilize life-threatening complications Address ABC problems first. In AKI, immediate threats include: - severe hyperkalemia; - pulmonary edema with respiratory compromise; - severe metabolic acidosis; - uremic pericarditis/encephalopathy; - severe symptomatic sodium disturbance; - toxin accumulation where extracorporeal removal is indicated. ### STEP 2 — Treat the cause Examples: - hypovolemia → judicious isotonic crystalloid/blood as appropriate; - hemorrhage → hemorrhage control + blood-product strategy; - sepsis → prompt infection/source control and hemodynamic management; - obstruction → catheterization, nephrostomy, stent, or urologic decompression according to level/cause; - GN/vasculitis/TMA → urgent disease-specific specialist pathway; - rhabdomyolysis → early fluids when appropriate, treat cause, monitor potassium/calcium/phosphate; - drug toxicity → stop culprit, adjust doses, antidote/extracorporeal therapy when indicated. ### STEP 3 — Stop ongoing kidney insults - stop nonessential nephrotoxins; - review ACEi/ARB, NSAIDs, diuretics and SGLT2 inhibitors in context rather than by rote; - adjust doses of renally cleared drugs; - avoid duplicate contrast/nephrotoxin exposure where clinically unnecessary; - check drug interactions and levels where relevant. ### STEP 4 — Optimize volume and perfusion KDIGO favors **isotonic crystalloids rather than colloids** for initial intravascular volume expansion in patients at risk of or with AKI when hemorrhagic shock is absent.[1] #### Balanced crystalloid vs 0.9% saline In the SMART trial, balanced crystalloids modestly reduced the composite of death, new KRT, or persistent renal dysfunction compared with saline in critically ill adults (14.3% vs 15.4%).[5] This supports frequent use of balanced crystalloid in many critically ill patients, but fluid choice must account for the indication, electrolyte/acid-base context, neurologic disease, and local protocol. **Do not give fluid merely because creatinine rose.** If the patient is congested or has cardiogenic physiology, repeated boluses can worsen pulmonary edema and renal venous congestion. ### STEP 5 — Monitor dynamically - urine output; - daily or more frequent creatinine/electrolytes according to severity; - potassium and bicarbonate; - fluid input/output; - daily weight in significant volume disturbance; - hemodynamics; - drug concentrations when indicated; - clinical response to interventions. NICE notes that daily creatinine measurement is typical for hospitalized patients with or at risk of AKI, adjusted to clinical need.[2] --- ## Pharmacotherapy principles ### Diuretics **STANDARD OF CARE:** Do **not** use loop diuretics to prevent AKI or to “convert” oliguric AKI to non-oliguric AKI. They are appropriate for **fluid overload/congestion** when there is a reasonable chance of diuretic response.[1,2] A rise in creatinine during effective decongestion in heart failure does not automatically mean diuretics should be stopped; interpret renal function alongside congestion, perfusion, blood pressure, and overall trajectory. ### Low-dose dopamine Do **not** use low-dose “renal-dose” dopamine to prevent or treat AKI.[1,2] ### ACE inhibitors and ARBs During significant acute volume depletion, vomiting/diarrhea, hypotension, or sepsis, temporary withholding may be reasonable and is specifically suggested by NICE in relevant acute illness.[2] However, once the acute process resolves, **reassess and restart evidence-based indications** rather than allowing accidental permanent discontinuation. --- ## Emergency hyperkalemia in AKI Hyperkalemia is one of the most important immediately reversible causes of death in severe AKI. #### First actions - confirm the result rapidly if pseudohyperkalemia is plausible, **without delaying treatment** when the patient is unstable or ECG changes are present; - obtain a 12-lead ECG and continuous monitoring for severe hyperkalemia; - stop exogenous potassium and contributing drugs; - stabilize the myocardium when ECG toxicity is present; - shift potassium intracellularly; - remove potassium from the body; - repeat potassium and glucose because rebound and hypoglycemia are common. #### UK Kidney Association 2023 adult emergency doses | Purpose | Treatment | Adult dose / note | |---|---|---| | **Protect the heart** | 10% calcium chloride | **10 mL IV over 5 min** in peri-arrest/cardiac arrest or according to local resuscitation protocol | | **Protect the heart** | 10% calcium gluconate | **30 mL IV over 10 min** for other patients with hyperkalemic ECG changes | | **Shift K into cells** | Soluble insulin + glucose | **10 units soluble insulin in 25 g glucose IV** for severe K ≥6.5 mmol/L; consider in moderate K 6.0–6.4 mmol/L | | Prevent post-insulin hypoglycemia | 10% glucose infusion | If pretreatment glucose <7 mmol/L, UKKA recommends **10% glucose 50 mL/hour for 5 h** after insulin-glucose | | **Adjunct shift** | Nebulized salbutamol | **10–20 mg nebulized** as adjunct in severe hyperkalemia; do not use as sole therapy | These doses are from UKKA guidance and may differ by jurisdiction/local resuscitation policy.[7] **Calcium does not lower serum potassium.** It temporarily reduces myocardial excitability risk while potassium-lowering therapy is initiated. **KRT should not be delayed** when severe hyperkalemia is refractory or expected to recur rapidly because of advanced renal failure, ongoing tissue breakdown, or inability to remove potassium medically.[1,7] --- ## Metabolic acidosis Treat the cause first: shock, sepsis, ketoacidosis, toxin, renal failure, etc. Sodium bicarbonate is **not a universal AKI therapy**. Consider it selectively when severe acidemia itself is harmful and bicarbonate therapy is physiologically appropriate, while avoiding sodium/volume overload and recognizing that severe refractory acidosis may require KRT. --- ## Kidney replacement therapy (KRT) ### Indications KDIGO recommends emergency KRT when there are **life-threatening changes in fluid, electrolyte, or acid-base balance**.[1] Common practical indications include: - refractory severe hyperkalemia; - refractory severe metabolic acidosis; - refractory pulmonary edema/volume overload causing hypoxemia; - uremic pericarditis; - uremic encephalopathy or severe symptomatic uremia; - selected dialyzable intoxications; - progressive complications when medical management is failing. #### What should NOT determine KRT alone - one creatinine value; - one BUN/urea value; - oliguria in isolation; - “stage 3 AKI” without clinical context. ### Timing when no emergency indication exists The **STARRT-AKI** trial randomized critically ill patients with severe AKI to accelerated vs standard KRT initiation. Accelerated initiation **did not reduce 90-day mortality** and was associated with more adverse events and greater dialysis dependence among survivors.[6] **STANDARD OF CARE implication:** In a patient without an urgent indication, do not start KRT solely because severe AKI has developed. Watch the clinical trajectory closely and start when complications, worsening physiology, or failure of conservative management justify it. ### Modality - **Intermittent hemodialysis:** efficient solute/volume removal; may be poorly tolerated in unstable patients. - **Continuous KRT (CKRT/CRRT):** often favored in severe hemodynamic instability or some neurocritical-care situations. - **Prolonged intermittent therapies (SLED/PIRRT):** hybrid option depending on local resources. Modality should reflect hemodynamics, neurologic status, solute-removal needs, staffing/resources, and local expertise—not an assumption that one modality is universally superior. --- ## Contrast-associated AKI: 2024 practice update NICE updated its iodinated-contrast recommendations in **October 2024**.[2] #### Key points - An **eGFR <30 mL/min/1.73 m²** is associated with a small but increased risk of AKI from iodinated contrast exposure. - **Do not delay emergency contrast imaging** if delaying contrast is likely to cause clinically significant harm. - For increased-risk patients, encourage **oral hydration** before and after IV iodinated contrast when appropriate. - For particularly high-risk inpatients (e.g., eGFR <30, kidney transplant, high contrast volume/repeat dose, first-pass intra-arterial exposure), consider IV volume expansion with **0.9% saline or isotonic sodium bicarbonate**. - NICE suggests considering temporary ACEi/ARB withholding in CKD with eGFR <30 around iodinated contrast. **Guideline conflict / nuance:** Contrast protocols differ among radiology, nephrology, and national guidance. Modern evidence has reduced previous estimates of contrast-caused AKI, especially for routine IV CT. The clinical harm of missing or delaying a time-critical diagnosis can exceed the renal risk. Use local radiology policy and patient-specific risk rather than a blanket “no contrast in AKI” rule. --- ## When to involve nephrology urgently NICE recommends discussion with nephrology within 24 hours when there is, among other situations:[2] - stage 3 AKI; - AKI with no clear cause; - inadequate response to treatment; - complications of AKI; - suspected vasculitis, glomerulonephritis, interstitial nephritis, or myeloma requiring specialist therapy; - kidney transplant; - advanced CKD (stage 4–5). **Immediate** nephrology/critical-care discussion is needed for potential KRT indications or severe rapidly evolving complications. --- ## Special clinical contexts ### Sepsis-associated AKI Mechanisms extend beyond simple “renal hypoperfusion” and include inflammatory, endothelial, microcirculatory, venous-congestion, and tubular-metabolic changes. Management centers on: - source control and antimicrobials; - hemodynamic resuscitation; - avoiding both under-resuscitation and fluid overload; - dose-adjusting renally cleared antimicrobials; - KRT when indicated. ### Heart failure / cardiorenal syndrome Creatinine can worsen from low forward flow, high venous pressure, neurohormonal activation, or treatment-related hemodynamic changes. In a clearly congested patient, blindly giving fluid because of AKI can be dangerous. Decongestion often remains necessary. ### Cirrhosis Consider: - hypovolemia/bleeding; - sepsis; - acute tubular injury; - nephrotoxins; - abdominal compartment physiology; - hepatorenal syndrome (HRS-AKI). HRS is a diagnosis requiring appropriate exclusion/treatment of competing causes; early hepatology/nephrology involvement is appropriate. ### Rhabdomyolysis - treat the cause; - give isotonic fluid early when appropriate and not volume-overloaded; - monitor potassium, calcium, phosphate, bicarbonate, CK and urine output; - do not use bicarbonate or mannitol routinely solely to prevent AKI without a specific indication; - dialyze for standard complications, not CK level alone. ### Pregnancy AKI requires obstetric-nephrology evaluation. Important causes include hemorrhage, sepsis, hyperemesis, preeclampsia/HELLP, acute fatty liver of pregnancy, TMA, cortical necrosis, and obstruction. Normal pregnancy creatinine is lower than in nonpregnant adults, so a “normal-range” creatinine may already represent significant renal dysfunction. ### Kidney transplant AKI differentials include rejection, obstruction, vascular complications, infection, volume/hemodynamic causes, calcineurin-inhibitor toxicity, and drug interactions. Involve the transplant team early. --- ## Prevention ### General prevention bundle For high-risk patients: - identify CKD and previous AKI; - monitor creatinine and urine output appropriately; - maintain adequate perfusion and avoid unnecessary hypotension; - avoid or minimize nephrotoxins; - use drug-dose adjustment and therapeutic monitoring; - avoid unnecessary contrast repetition; - prevent/treat sepsis promptly; - prevent severe dehydration; - use protocolized perioperative risk management when indicated. NICE recommends active AKI risk assessment in acutely ill adults with CKD, heart failure, liver disease, diabetes, prior AKI, oliguria, hypovolemia, sepsis, recent nephrotoxin exposure, obstruction risk, deteriorating early-warning scores, or age ≥65 years.[2] --- ## Monitoring and reassessment ### In-hospital Track: - urine output hourly when severe/unstable; - creatinine and electrolytes at a frequency dictated by trajectory; - potassium more frequently after emergency therapy; - bicarbonate/pH when acid-base disturbance is important; - daily weights and fluid balance in major volume disturbance; - drug levels where required; - nutritional status; - recovery vs persistent AKI. ### After discharge KDIGO recommends evaluating patients **3 months after AKI** for resolution, new CKD, or worsening pre-existing CKD.[1] NICE advises post-AKI creatinine monitoring based on stability at discharge and considering nephrology referral when eGFR is **≤30 mL/min/1.73 m²** after recovery.[2] Practical follow-up should also address: - blood pressure; - albuminuria/proteinuria where appropriate; - medication reconciliation and restart of indicated drugs; - recurrent AKI prevention; - avoidance of unnecessary NSAIDs; - cardiovascular/CKD risk management. --- ## Anticipating deterioration | Warning sign | Why it matters | Immediate response | |---|---|---| | Rapidly rising K or ECG changes | Arrhythmic death | Cardiac protection + K shift/removal + nephrology/KRT planning | | Falling urine output → anuria | Severe AKI or obstruction | Check catheter/bladder, hemodynamics, imaging, obstruction | | Rising O2 requirement + edema | Pulmonary edema/volume overload | Respiratory support, diuresis if responsive, KRT if refractory | | New confusion, pericarditic pain/rub | Uremic complication | Urgent nephrology/KRT assessment | | Hematuria + proteinuria + systemic features | Rapidly progressive GN | Serologies + urgent nephrology; biopsy/immunotherapy pathway | | Thrombocytopenia + hemolysis | TMA | Immediate hematology/nephrology pathway | | Severe hypertension + AKI | Malignant HTN/TMA | Controlled BP reduction, end-organ assessment | | Persistent AKI >7 days | AKD transition | Reassess diagnosis, nephrotoxins, obstruction, biopsy need, follow-up plan | --- ## Common pitfalls | Pitfall | Why it fails | Better approach | |---|---|---| | Calling every creatinine rise “dehydration” | Misses congestion, GN, obstruction, TMA, ATI | Establish physiology and cause | | Giving repeated fluids without reassessment | Can worsen pulmonary edema and venous congestion | Give fluid only for a plausible fluid-responsive state and reassess | | Relying on FeNa alone | Many false-low and false-high states | Integrate history, exam, urine sediment, hemodynamics | | Using diuretics to “treat the creatinine” | Does not reverse renal injury | Use for clinically important volume overload | | Waiting for severe creatinine before checking urine | Delays GN/obstruction clues | Early urinalysis and sediment | | Refusing emergency contrast because of AKI | Can delay diagnosis of PE, aortic catastrophe, bleeding, stroke pathway, etc. | Weigh diagnostic harm vs renal risk; emergency imaging often proceeds | | Dialyzing by BUN/creatinine threshold | Ignores actual indication and trial evidence | Dialyze for physiology/complications/trajectory | | Forgetting medication restart after recovery | Permanent loss of beneficial ACEi/ARB/other therapy | Reconcile and restart when safe | | Discharging without follow-up | Misses AKD/CKD and recurrence risk | Define post-AKI kidney monitoring | --- ## Diagnostic and management algorithm ```text Creatinine rise and/or oliguria meets AKI criteria ↓ 1. Confirm trend + assess severity - K, bicarbonate/pH, oxygenation, volume status, urine output ↓ 2. Any immediate life threat? - severe hyperK / pulmonary edema / severe acidosis / uremic complication ├─ YES → emergency treatment + nephrology/critical care + consider KRT └─ NO ↓ 3. Search for reversible cause - hypovolemia/shock? - congestion/heart failure? - obstruction? - nephrotoxin/drug? - sepsis? - GN/AIN/TMA/rhabdo/myeloma? ↓ 4. Core tests - urinalysis + sediment - electrolytes/CBC - bladder scan/ultrasound if obstruction plausible - targeted serology/CK/hemolysis tests as indicated ↓ 5. Treat cause + optimize perfusion/volume - fluid only if appropriate - decongest if overloaded - relieve obstruction - stop/adjust nephrotoxins ↓ 6. Reassess repeatedly - creatinine trend, urine output, K, acid-base, volume status ↓ 7. Persistent/worsening AKI, stage 3, unclear cause, or complications? ├─ YES → nephrology; consider biopsy/KRT └─ NO → continue cause-directed management ↓ 8. Discharge only with recovery trajectory + medication plan + kidney follow-up ``` --- ## STANDARD OF CARE vs EMERGING EVIDENCE vs EXPERIMENTAL ### STANDARD OF CARE - KDIGO creatinine/urine-output diagnosis and staging.[1] - Cause-directed treatment and repeated clinical reassessment. - Isotonic crystalloid for true intravascular volume depletion, avoiding indiscriminate fluid loading.[1] - Stop/adjust nephrotoxins and renally cleared drugs. - Do not use low-dose dopamine.[1,2] - Do not use loop diuretics to prevent/treat AKI except to manage volume overload.[1,2] - Urgent KRT for life-threatening electrolyte, acid-base, volume, or uremic complications.[1] - Do not start KRT solely because a creatinine/BUN threshold has been reached.[1,6] - Post-AKI follow-up for CKD/AKD risk.[1,4] ### EMERGING EVIDENCE / ACTIVE IMPLEMENTATION - Biomarker-supported risk stratification (e.g., tubular-stress/injury biomarkers) in selected settings. - Electronic AKI prediction and decision-support systems. - More formal AKI-to-AKD transition pathways and structured post-discharge clinics. - Precision fluid/hemodynamic strategies using dynamic responsiveness and congestion measures. - Broader integration of nephrotoxin stewardship programs. ### EXPERIMENTAL / NOT ROUTINE FOR GENERAL AKI - Using a novel biomarker alone to diagnose the cause of AKI or decide KRT. - “Renal-protective” pharmacologic agents without proven patient-centered benefit. - Routine extracorporeal therapy solely to remove inflammatory mediators in sepsis-associated AKI outside established indications/trials. --- ## Current guideline changes and conflicts (2024–2026) ### 1. Contrast-associated AKI risk has been reframed NICE 2024 now emphasizes an increased risk mainly at **eGFR <30**, uses updated terminology “contrast-associated AKI,” and explicitly warns against delaying clinically important emergency contrast imaging.[2] ### 2. KDIGO AKI update is imminent but not final KDIGO released a **2026 public-review draft** covering AKI and AKD, expanded biomarkers/risk prediction, fluids/hemodynamics, nephrotoxin stewardship, contrast-associated AKI, KRT timing/modality/dose/discontinuation, and follow-up.[8] Until final publication, the 2012 guideline remains the formal KDIGO standard. ### 3. Early routine KRT has lost momentum STARRT-AKI provides strong evidence against automatic accelerated KRT in severe AKI without urgent complications.[6] ### 4. Balanced crystalloids increasingly favored in many acute-care pathways SMART demonstrated a modest kidney-centered composite benefit compared with saline in critically ill adults.[5] Fluid composition remains context-dependent rather than absolute. --- ## Landmark and practice-shaping evidence ### SMART (2018) 15,802 critically ill adults were randomized in a pragmatic cluster-crossover design. Major adverse kidney events within 30 days occurred in **14.3%** with balanced crystalloids vs **15.4%** with saline (P=0.04).[5] **Takeaway:** A small absolute benefit supports balanced crystalloid as a reasonable default in many critically ill adults, but effect size is modest and context matters. ### STARRT-AKI (2020) Nearly 3000 critically ill patients with severe AKI were assigned to accelerated or standard KRT initiation. Accelerated KRT did **not** reduce 90-day mortality; adverse events were more frequent, and KRT dependence among survivors was higher.[6] **Takeaway:** In the absence of emergency indications, clinical watchfulness is often preferable to automatic early dialysis. ### AKI–AKD continuum (ADQI) The ADQI consensus formalized AKD as kidney disease persisting 7–90 days after an acute event, emphasizing that kidney recovery is a trajectory, not a binary discharge diagnosis.[4] --- ## Exam-focused review ### USMLE Step 1 Know: - afferent vs efferent arteriolar physiology; - how NSAIDs and ACEi/ARB can reduce GFR under vulnerable hemodynamic conditions; - tubular injury and muddy brown casts; - glomerular hematuria/RBC casts; - obstruction physiology; - why creatinine lags behind true GFR decline. ### USMLE Step 2 CK Prioritize: - volume status and cause; - urinalysis/sediment; - ultrasound when obstruction is possible; - stopping nephrotoxins; - treating hyperkalemia and pulmonary edema before “workup completion.” ### Step 3 / Resident Focus on: - mixed hemodynamic + structural AKI; - drug dosing and restart plans; - when fluid is harmful; - nephrology referral; - KRT indications vs timing; - post-AKI follow-up. ### MRCP / ABIM / Boards High-yield discriminators: - low FeNa is not synonymous with prerenal AKI; - loop diuretics do not improve AKI recovery; - stage can be determined by urine output; - emergency contrast should not be reflexively withheld; - dialysis is based on complications/trajectory, not a creatinine number; - hematuria + proteinuria + AKI should trigger GN thinking; - thrombocytopenia + hemolysis + AKI should trigger TMA thinking. --- ## Original MCQs ### Question 1 A 72-year-old man with vomiting and diarrhea has a creatinine rise from 1.0 to 1.4 mg/dL within 36 hours. Urine output is preserved. Which statement is most accurate? A. He does not have AKI because creatinine is <2 mg/dL B. He has KDIGO stage 1 AKI C. He has stage 2 AKI D. AKI requires oliguria E. AKI can only be diagnosed after 7 days **Answer: B.** A rise ≥0.3 mg/dL within 48 hours meets AKI criteria and stage 1 severity.[1] --- ### Question 2 A patient with severe decompensated heart failure, pulmonary edema, high JVP, and worsening creatinine receives repeated 1-L saline boluses because the creatinine is rising. Which is the best critique? A. All AKI should receive at least 3 L crystalloid B. Rising creatinine proves intravascular depletion C. Fluid can worsen venous congestion and pulmonary edema; volume therapy should follow physiology D. Diuretics are contraindicated in all AKI E. Dialysis should be started based on creatinine alone **Answer: C.** AKI in heart failure may reflect congestion and low effective perfusion; indiscriminate fluid can worsen both respiratory status and renal venous pressure. --- ### Question 3 A patient with AKI has potassium 7.0 mmol/L, a widened QRS, and no dialysis catheter. What is the immediate priority? A. Wait for repeat potassium before treatment B. Give IV calcium to stabilize the myocardium while initiating potassium-lowering therapy C. Give furosemide only D. Start oral sodium bicarbonate and review tomorrow E. Obtain renal biopsy **Answer: B.** Hyperkalemic ECG toxicity is immediately life-threatening. Calcium protects the myocardium but does not lower K; simultaneous shift/removal therapy and urgent nephrology/KRT planning are required.[7] --- ### Question 4 A critically ill patient has KDIGO stage 3 AKI but potassium, pH, oxygenation, and volume status are controlled. Which statement best reflects modern evidence? A. Stage 3 AKI mandates immediate dialysis in all patients B. Creatinine >3× baseline mandates dialysis C. Accelerated KRT improves 90-day mortality D. In the absence of urgent indications, KRT timing should be individualized and close monitoring is appropriate E. KRT should be withheld even if refractory hyperkalemia develops **Answer: D.** STARRT-AKI found no mortality benefit from accelerated KRT in severe AKI without urgent indications.[6] --- ### Question 5 A 69-year-old with AKI has hematuria, proteinuria, pulmonary infiltrates, and falling hemoglobin. What should be prioritized? A. Diagnose prerenal AKI from FeNa alone B. Assume contrast nephropathy C. Urgent evaluation for pulmonary-renal vasculitis/anti-GBM disease with nephrology involvement D. Give NSAIDs for pleuritic pain E. Wait for spontaneous recovery **Answer: C.** AKI with an active urine sediment and pulmonary hemorrhage features is a nephrologic emergency. --- ### Question 6 A hemodynamically stable patient with suspected aortic dissection has AKI and eGFR 24 mL/min/1.73 m². CT angiography is urgently needed. Which is the best approach? A. Delay contrast for several days until creatinine normalizes B. Cancel definitive imaging because eGFR is <30 C. Proceed with time-critical contrast imaging while using appropriate renal-risk mitigation D. Give N-acetylcysteine and postpone imaging E. Dialyze prophylactically before CT **Answer: C.** NICE 2024 explicitly states not to delay emergency iodinated contrast when the risk of delay is clinically significant.[2] --- ## Acute management checklist ### Recognition - [ ] Compare creatinine with baseline and stage AKI. - [ ] Measure and trend urine output. - [ ] Check K, bicarbonate/pH, volume status, oxygenation. - [ ] Obtain urinalysis early. ### Immediate threats - [ ] ECG if hyperkalemia suspected/severe. - [ ] Treat hyperkalemic ECG toxicity immediately. - [ ] Treat pulmonary edema and severe acidosis. - [ ] Call nephrology/critical care early for KRT-level complications. ### Cause - [ ] Assess hypovolemia vs congestion vs shock. - [ ] Review all medications and recent exposures. - [ ] Check for urinary obstruction. - [ ] Screen for GN/AIN/TMA/rhabdo/myeloma when context suggests. ### Management - [ ] Give isotonic crystalloid only when a fluid-responsive state is plausible. - [ ] Stop/adjust nephrotoxins and renally cleared drugs. - [ ] Treat infection/bleeding/obstruction/cardiac cause. - [ ] Use diuretics for congestion, not to “cure AKI.” - [ ] Reassess after every major intervention. ### Discharge - [ ] Document AKI episode and peak stage. - [ ] Define creatinine/electrolyte follow-up. - [ ] Reconcile temporarily held medications. - [ ] Assess CKD/albuminuria/BP risk. - [ ] Educate regarding dehydration and NSAID/nephrotoxin risk. --- ## References 1. **Kidney Disease: Improving Global Outcomes (KDIGO) Acute Kidney Injury Work Group.** KDIGO Clinical Practice Guideline for Acute Kidney Injury. *Kidney Int Suppl.* 2012;2:1-138. Official guideline: https://kdigo.org/guidelines/acute-kidney-injury/ 2. **National Institute for Health and Care Excellence (NICE).** Acute kidney injury: prevention, detection and management. NG148. Published 2019; updated 16 October 2024. https://www.nice.org.uk/guidance/ng148 3. **Susantitaphong P, Cruz DN, Cerda J, et al.** World incidence of AKI: a meta-analysis. *Clin J Am Soc Nephrol.* 2013;8(9):1482-1493. PMID: 23744003. doi:10.2215/CJN.00710113 4. **Chawla LS, Bellomo R, Bihorac A, et al.; ADQI 16 Workgroup.** Acute kidney disease and renal recovery: consensus report of the Acute Disease Quality Initiative (ADQI) 16 Workgroup. *Nat Rev Nephrol.* 2017;13:241-257. doi:10.1038/nrneph.2017.2 5. **Semler MW, Self WH, Wanderer JP, et al.; SMART Investigators.** Balanced Crystalloids versus Saline in Critically Ill Adults. *N Engl J Med.* 2018;378:829-839. doi:10.1056/NEJMoa1711584 6. **STARRT-AKI Investigators.** Timing of Initiation of Renal-Replacement Therapy in Acute Kidney Injury. *N Engl J Med.* 2020;383:240-251. doi:10.1056/NEJMoa2000741 7. **Alfonzo A, Harrison A, Baines R, Chu A, Mann S, MacRury M.** UK Kidney Association Clinical Practice Guideline: Management of Hyperkalaemia in Adults. Published 19 December 2023. https://www.ukkidney.org/health-professionals/guidelines/treatment-acute-hyperkalaemia-adults-0 8. **Kidney Disease: Improving Global Outcomes (KDIGO).** Acute Kidney Injury (AKI) and Acute Kidney Disease (AKD): 2026 Guideline Public Review information. Public review closed 11 May 2026; final guideline pending at time of review. https://kdigo.org/guidelines/acute-kidney-injury/ --- ### NEXT-TOPIC LEDGER **Completed today:** Acute Kidney Injury **Do not repeat normalized title:** `acute-kidney-injury` **Suggested future linked topics:** Acute kidney disease; Chronic kidney disease; Hyperkalemia; Glomerulonephritis; Acute interstitial nephritis; Rhabdomyolysis; Kidney replacement therapy; Contrast-associated AKI7:["$","$L17",null,{"article":{"id":"medical-atrial-fibrillation","title":"Atrial Fibrillation","slug":"atrial-fibrillation","description":"Atrial fibrillation (AF) is a supraventricular tachyarrhythmia with disorganized atrial activation and ineffective atrial contraction. 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