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: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.**19:T9887,## 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](/library/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](/library/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.**1a:Tebc2,## One-minute summary **Atrial fibrillation (AF)** is a supraventricular tachyarrhythmia characterized by chaotic atrial electrical activation and ineffective atrial contraction. On ECG it produces **irregularly irregular RR intervals** (when AV conduction is intact), absence of discrete organized P waves, and fibrillatory atrial activity. A standard 12-lead ECG can establish the diagnosis; ambulatory/device tracings require clinician-confirmed electrocardiographic evidence rather than pulse irregularity alone.[1,2] AF management has four simultaneous goals. The **2024 ESC AF-CARE pathway** organizes them as: **[C] Comorbidity and risk-factor management; [A] Avoid stroke and thromboembolism; [R] Reduce symptoms with rate and rhythm control; [E] Evaluate and dynamically reassess.**[2] ### Immediate priorities 1. **Is the patient hemodynamically unstable because of AF?** If yes, perform urgent synchronized electrical cardioversion; do not delay a life-saving shock for a prolonged anticoagulation workup.[1,2] 2. **If stable, identify and treat precipitants** such as sepsis, hypovolemia, acute coronary syndrome, pulmonary embolism, hypoxia, hyperthyroidism, electrolyte disturbance, alcohol excess, or decompensated heart failure. 3. Choose **rate control, rhythm control, or both**, based on symptoms, AF duration, ventricular function, comorbidity, age, patient preference, and the potential prognostic benefit of early rhythm control.[1,2,8] 4. Assess **stroke risk independently of apparent rhythm success.** In the 2023 ACC/AHA/ACCP/HRS guideline, anticoagulation is recommended when estimated annual thromboembolic risk is ≥2% (roughly CHA₂DS₂-VASc ≥2 in men or ≥3 in women) and is reasonable at 1–2%/year.[1] The 2024 ESC guideline instead uses **CHA₂DS₂-VA** (sex removed): anticoagulation should be considered at 1 and is recommended at ≥2.[2] 5. **DOACs are preferred to warfarin** in eligible patients, except for mechanical heart valves and clinically significant mitral stenosis where a vitamin K antagonist remains standard.[1,2] ### Major 2024–2026 practice points - ESC 2024 **reduced the known-duration threshold for un-anticoagulated early cardioversion from 48 to 24 hours**. If AF is known to have lasted >24 h, ESC recommends ≥3 weeks therapeutic anticoagulation or transesophageal echocardiography (TOE/TEE) to exclude thrombus before elective cardioversion.[2,3] - The 2023 US guideline retains a **≥48-hour** threshold for a Class I requirement for 3 weeks of uninterrupted anticoagulation or imaging before elective cardioversion, while also emphasizing that risk is continuous and depends on patient substrate rather than duration alone.[1] - Catheter ablation is no longer simply a “last resort.” It is a first-line rhythm-control option in selected symptomatic patients, especially paroxysmal AF; it has particularly important outcome data in AF with HFrEF.[1,2,10] - Device-detected subclinical AF is **not automatically equivalent** to clinical AF. ARTESiA showed fewer strokes/systemic emboli with apixaban but more major bleeding, whereas NOAH-AFNET 6 found no significant efficacy advantage for edoxaban and more harm on a composite safety outcome.[11,12] - New **2026 AHA/ACC AF performance and quality measures** reinforce annual validated stroke-risk assessment, appropriate DOAC use, risk-factor modification, shared decision-making, and rhythm-control consideration in HFrEF.[13] --- ## Core concepts ### Why AF matters AF is not merely an irregular pulse. Its clinical consequences arise from several interacting mechanisms: - **loss of coordinated atrial contraction** → reduced ventricular filling, especially important in stiff ventricles; - **rapid or irregular ventricular response** → impaired cardiac output and possible tachycardia-induced cardiomyopathy; - **atrial stasis and endothelial dysfunction**, particularly in the left atrial appendage (LAA) → thrombus formation and embolic stroke; - **atrial remodeling** → electrical and structural changes that promote persistence (“AF begets AF”); - **shared disease substrate** with hypertension, obesity, sleep apnea, diabetes, CKD, heart failure, vascular disease, and aging. AF is the most common sustained arrhythmia in clinical practice. Contemporary US data cited by the 2026 AHA/ACC measures estimate more than **10.5 million US adults** carry an AF diagnosis and lifetime risk approaches **1 in 3**.[13] --- ## Definition and electrocardiographic diagnosis ### ECG features Typical AF shows: - irregularly irregular ventricular rhythm; - no consistent P waves; - variable fibrillatory baseline activity; - usually narrow QRS unless pre-existing bundle-branch block, rate-related aberrancy, ventricular pacing, or pre-excitation is present. A regular rhythm argues against ordinary AF and should prompt reconsideration (e.g., atrial flutter with fixed conduction, paced rhythm, junctional rhythm, AV block). #### Confirm the rhythm Consumer wearables, photoplethysmography, automated cuff alerts, and implantable devices are useful for screening and surveillance, but **a clinical AF diagnosis requires reviewable electrocardiographic evidence**. The 2024 ESC guideline accepts a 12-lead ECG or sufficiently clear ambulatory ECG evidence; older research definitions commonly use episodes ≥30 seconds, although management decisions should consider the clinical context and AF burden rather than treating “30 seconds” as a biologic cliff.[2] --- ## Classification ### Conventional temporal classification | AF pattern | Definition | Clinical implication | |---|---|---| | **First diagnosed AF** | First documented episode, regardless of duration | Does not imply mechanism or future course | | **Paroxysmal AF** | Terminates spontaneously or with intervention within 7 days | Often more amenable to early rhythm control/ablation | | **Persistent AF** | Sustained >7 days | Greater atrial remodeling; cardioversion often required | | **Long-standing persistent AF** | Continuous AF >12 months when rhythm control remains pursued | Lower rhythm-control success; careful selection needed | | **Permanent AF** | Patient and clinician accept AF and no longer pursue sinus rhythm | A treatment decision, not an irreversible electrophysiologic state | ### 2023 ACC/AHA disease-stage framework The US guideline reframed AF as a progressive disease continuum:[1] - **Stage 1 — At risk:** risk factors present but no structural/electrical findings. - **Stage 2 — Pre-AF:** structural/electrical findings that predispose to AF but no prior AF episode. - **Stage 3 — AF:** includes paroxysmal, persistent, long-standing persistent, and patients after successful ablation. - **Stage 4 — Permanent AF:** decision made not to pursue further rhythm-control attempts. **Why this matters:** prevention and risk-factor treatment begin *before* AF becomes persistent. --- ## Epidemiology and risk factors AF prevalence rises sharply with age and is strongly associated with accumulated cardiovascular risk. Important modifiable and nonmodifiable contributors include: #### Cardiovascular - hypertension; - coronary artery disease / prior MI; - heart failure (HFrEF or HFpEF); - valvular disease, especially mitral disease; - cardiomyopathy; - congenital heart disease; - atrial enlargement; - cardiac surgery. #### Metabolic / systemic - increasing age; - obesity; - diabetes mellitus; - chronic kidney disease; - hyperthyroidism; - systemic inflammation/sepsis; - pulmonary disease and hypoxemia; - pulmonary embolism; - obstructive sleep apnea. #### Lifestyle / exposures - heavy alcohol use and binge drinking (“holiday heart”); - smoking; - physical inactivity; - extreme endurance exercise in some individuals; - stimulant/drug exposure in selected cases. #### Genetic / familial Familial AF and pathogenic variants can occur, particularly in early-onset disease. In unusually young patients without conventional risk factors, consider inherited cardiomyopathy/channelopathy or an accessory pathway depending on phenotype. --- ## Pathophysiology ### Trigger + substrate model Most AF requires both: 1. **Triggers**, commonly rapidly firing foci from the pulmonary veins; and 2. **A vulnerable atrial substrate**, produced by fibrosis, dilation, inflammation, autonomic changes, cellular calcium-handling abnormalities, and conduction heterogeneity. Repeated AF itself promotes: - shortening of atrial refractory periods; - calcium-handling changes; - fibrosis and atrial dilation; - loss of effective contractility. This explains why early rhythm control and aggressive risk-factor treatment can be more successful before long-standing remodeling develops. ### Stroke mechanism Thromboembolism is driven by a Virchow-triad-like interaction: - atrial/LAA blood stasis; - endothelial/endocardial dysfunction; - prothrombotic systemic state. Most AF-related cardiac thrombi form in the LAA, which is why LAA occlusion/exclusion strategies exist. However, AF also marks a broader **atrial cardiomyopathy and vascular-risk phenotype**, helping explain why stroke risk does not disappear immediately when sinus rhythm is restored. ### Tachycardia-/arrhythmia-induced cardiomyopathy Persistent rapid AF can cause or worsen LV systolic dysfunction. Clues include: - newly reduced LVEF without another clear cause; - high AF burden / sustained tachycardia; - substantial LVEF improvement after rhythm control. This is an especially important population because rhythm control—often catheter ablation—may improve ventricular function and clinical outcomes.[1,9,10] --- ## Clinical presentation AF ranges from completely asymptomatic to shock. Common symptoms: - palpitations; - dyspnea; - reduced exercise tolerance; - fatigue; - chest discomfort; - lightheadedness / presyncope; - anxiety-like awareness of irregular heartbeat; - worsening heart failure; - stroke/TIA as the first manifestation. #### Red flags - hypotension/shock; - ongoing ischemic chest pain; - acute pulmonary edema or severe hypoxemia; - syncope with very rapid or very slow rate; - altered mental status from poor perfusion; - pre-excited AF with very rapid, irregular, wide-complex rhythm; - focal neurologic deficit suggesting stroke; - severe bradycardia/pauses after AF termination; - suspected acute coronary syndrome, PE, myocarditis, or aortic catastrophe. --- ## History A focused but high-yield AF history should establish: ### Episode characteristics - exact or best-estimate onset time; - continuous vs intermittent symptoms; - prior episodes and spontaneous conversion; - prior cardioversion/ablation; - prior antiarrhythmic drugs and failures; - rate-control medication adherence. ### Thromboembolic history - prior ischemic stroke/TIA/systemic embolism; - anticoagulant name, dose, adherence, last dose; - missed DOAC doses; - warfarin INR history/time in therapeutic range; - prior bleeding; - LAAO history. ### Precipitants - fever/infection; - vomiting/diarrhea/dehydration; - alcohol binge; - stimulant use; - thyrotoxic symptoms; - recent surgery; - hypoxia/OSA; - chest pain/PE symptoms; - acute HF symptoms. ### Structural heart disease - MI/CAD; - heart failure; - valvular disease; - cardiomyopathy; - congenital heart disease; - prior echo/LVEF. ### Medication risks - QT-prolonging drugs; - digoxin; - AV nodal blockers; - CYP3A4/P-gp interacting drugs; - antiarrhythmics; - renal/hepatic impairment affecting DOAC exposure. --- ## Examination Assess: - heart rate and rhythm; - blood pressure and perfusion; - oxygen saturation and respiratory distress; - signs of congestion (JVP, edema, crackles); - murmurs suggesting valve disease; - thyrotoxicosis signs; - neurologic deficit; - evidence of infection/sepsis; - volume depletion; - pulse deficit. **Clinical pearl:** A radial pulse can underestimate ventricular rate during AF because some ventricular contractions generate insufficient stroke volume to produce a palpable peripheral pulse. Use ECG/monitoring when the rate matters. --- ## Diagnosis and initial investigations ### 12-lead ECG Confirm AF and look for: - ventricular rate; - QRS width; - ischemia; - prior infarction; - LVH; - bundle-branch block; - pre-excitation; - QT interval (important before many antiarrhythmics). ### Basic laboratory workup Tailor to context, commonly: - CBC; - electrolytes, including potassium and magnesium; - renal function; - liver tests when anticoagulant/antiarrhythmic choice requires; - TSH (especially new AF or thyrotoxic symptoms); - glucose/HbA1c and cardiovascular-risk assessment; - troponin when ACS/ischemia is clinically suspected rather than reflexively in every uncomplicated AF episode. ### Echocardiography A transthoracic echocardiogram usually assesses: - LVEF; - LA size; - valve disease; - LVH; - right-heart disease; - structural cardiomyopathy. TEE/TOE is used when left atrial/LAA thrombus exclusion will change cardioversion or procedural management. ### Ambulatory monitoring Useful for: - intermittent symptoms; - quantifying AF burden; - rate-control adequacy; - post-ablation surveillance; - correlating symptoms with rhythm; - detecting pauses/bradycardia. --- ## Differential diagnosis of an irregular rhythm | Rhythm / condition | Distinguishing features | |---|---| | **Atrial flutter with variable block** | Organized flutter waves, often atrial rate ~300/min; ventricular rhythm may be irregular | | **Multifocal atrial tachycardia (MAT)** | Irregular rhythm with ≥3 distinct P-wave morphologies and visible isoelectric baseline; often COPD/hypoxemia | | **Sinus rhythm with frequent PACs** | Underlying sinus P waves with premature atrial beats | | **Sinus arrhythmia** | P before each QRS; respiratory pattern, often younger patients | | **Frequent PVCs** | Premature wide complexes; underlying organized atrial rhythm | | **Pre-excited AF** | Very rapid irregular wide-complex tachycardia, variable QRS morphology; dangerous accessory-pathway conduction | --- ## Acute management algorithm ```text ECG-confirmed atrial fibrillation ↓ Is AF causing hemodynamic instability? (hypotension/shock, ischemia, pulmonary edema, critical hypoperfusion) ├─ YES → immediate synchronized electrical cardioversion │ + anticoagulation as soon as safely feasible │ + treat precipitating cause │ └─ NO ↓ Stable: assess - ventricular rate and symptoms - LVEF / HF status - pre-excitation? - AF duration / anticoagulation status - trigger (sepsis, hypoxia, thyroid, ACS, PE, alcohol, etc.) ↓ Pre-excited AF? ├─ YES → avoid AV-nodal blockers │ stable: IV procainamide or ibutilide / cardioversion │ unstable: electrical cardioversion └─ NO ↓ Need immediate rhythm restoration? ├─ NO → rate control + trigger treatment + stroke prevention └─ YES → cardioversion strategy based on duration and thrombus risk ↓ Long-term plan: AF-CARE comorbidities + anticoagulation + rate/rhythm strategy + reassessment ``` --- ## Hemodynamically unstable AF **STANDARD OF CARE:** If AF is causing acute or worsening hemodynamic instability, synchronized electrical cardioversion is the fastest and preferred treatment.[1,2] Examples: - shock/hypotension attributable to the tachyarrhythmia; - ongoing myocardial ischemia; - acute pulmonary edema; - severe low-output symptoms. Provide procedural sedation if feasible **without delaying life-saving cardioversion**. Confirm synchronization before the shock. Escalate energy according to device/local protocol if unsuccessful. Anticoagulation should be initiated as soon as safely possible around emergency cardioversion, but anticoagulation logistics must not postpone immediate resuscitative treatment.[1,2] --- ## Stable AF with rapid ventricular response: rate control ### First treat the patient, not just the monitor Before adding AV-nodal blockade, ask: - Is tachycardia compensatory for sepsis, hemorrhage, hypoxia, PE, or shock? - Is there decompensated HFrEF? - Is the QRS wide/irregular suggesting pre-excitation? - Is blood pressure adequate? Treating a compensatory tachycardia with aggressive rate-control drugs can worsen shock. ### Guideline-supported acute rate-control choices In **hemodynamically stable AF with RVR**, the 2023 ACC/AHA guideline recommends a beta blocker or nondihydropyridine calcium-channel blocker (diltiazem/verapamil) when **LVEF >40%**. Digoxin can be considered if those agents are ineffective or contraindicated; IV magnesium may be a useful adjunct. In critically ill patients or decompensated HF where standard AV-nodal blockers are unsuitable, IV amiodarone may be considered.[1] #### Common adult rate-control doses (2023 ACC/AHA table) | Drug | Acute IV regimen | Oral maintenance | Key cautions | |---|---|---|---| | **Metoprolol tartrate** | 2.5–5 mg IV over 2 min; up to 3 doses | 25–200 mg twice daily | Hypotension, bradycardia, bronchospasm; titrate in HF | | **Esmolol** | 500 mcg/kg bolus over 1 min, then 50–300 mcg/kg/min | — | Short half-life useful when rapid titration desired | | **Diltiazem** | 0.25 mg/kg IV over 2 min; may repeat 0.35 mg/kg; then 5–15 mg/h | ER 120–360 mg/day | **Avoid in HFrEF** / significant LV systolic dysfunction | | **Verapamil** | 5–10 mg IV over ≥2 min; may repeat; infusion up to 20 mg/h | ER 180–480 mg/day | **Avoid in HFrEF**, hypotension, AV block | | **Digoxin** | 0.25–0.5 mg IV, then 0.25 mg q6h; max 1.5 mg/24 h | 0.0625–0.25 mg/day | Renal clearance; slower onset; toxicity/interactions | | **Amiodarone** | 150–300 mg IV over 1 h, then 10–50 mg/h over 24 h | Usually 100–200 mg/day when used chronically | Can cardiovert → thromboembolic considerations; thyroid/lung/liver toxicity | Doses are guideline examples, not automatic prescriptions. Renal function, age, weight, BP, conduction disease, HF, and local protocols matter.[1] ### Rate target For many stable patients without severe HF, a **lenient resting rate <110 bpm** is a reasonable initial target if symptoms are controlled. RACE II found lenient control noninferior to stricter control in a selected population; however, patients with arrhythmia-induced cardiomyopathy, persistent symptoms, CRT pacing needs, or HF may require more stringent individualized control.[1] **Board trap:** “Heart rate 130” does not prove the AF is the primary disease process. In septic shock, the correct treatment may be source control and resuscitation rather than escalating diltiazem. --- ## Pre-excited AF (WPW): a critical exception Pre-excited AF can conduct extremely rapidly down an accessory pathway and degenerate into ventricular fibrillation. #### ECG clues - very fast irregular rhythm; - wide complexes; - variable QRS morphology; - very short RR intervals; - known WPW may or may not be documented previously. #### Management **Unstable:** immediate synchronized electrical cardioversion.[1] **Stable:** IV **procainamide or ibutilide** is recommended as a pharmacologic option, or proceed to cardioversion.[1] #### DO NOT give AV-nodal blockers The 2023 ACC/AHA guideline classifies the following as **harmful/contraindicated** in pre-excited AF because AV-node block may accelerate accessory-pathway conduction and precipitate VF:[1] - adenosine; - beta blockers; - diltiazem; - verapamil; - digoxin; - **amiodarone**. Definitive therapy is catheter ablation of the accessory pathway.[1] --- ## Rhythm control: who benefits? The old paradigm “rate control for most, rhythm control only for symptoms” has shifted. Rhythm control is considered when: - symptoms persist despite adequate rate control; - AF is recently diagnosed and patient has cardiovascular risk where early rhythm control may improve outcomes; - AF is causing or worsening cardiomyopathy/HF; - rate control is difficult; - the patient strongly prefers sinus rhythm; - maintaining sinus rhythm may improve exercise capacity or quality of life; - AF is paroxysmal and catheter ablation is an attractive first-line strategy. ### EAST-AFNET 4 changed the strategy In 2,789 patients with early AF (median 36 days since diagnosis) and cardiovascular conditions, early rhythm control reduced the composite of cardiovascular death, stroke, or hospitalization for worsening HF/ACS: **3.9 vs 5.0 events per 100 person-years; HR 0.79** over median 5.1 years.[8] **Clinical implication:** Rhythm control is not merely cosmetic symptom treatment in all patients; in selected recently diagnosed AF, starting rhythm control early can improve cardiovascular outcomes. --- ## Cardioversion ### Electrical vs pharmacologic Electrical cardioversion is: - mandatory in hemodynamic instability; - highly effective when rapid restoration is desired; - often chosen for persistent AF or failed drug conversion. Pharmacologic cardioversion may be appropriate in stable patients, depending on structural heart disease, QT interval, renal function, drug availability, and local protocol. ### Common pharmacologic options | Agent | Typical role | Major limitations | |---|---|---| | **Flecainide** | Conversion / pill-in-the-pocket in selected patients without structural heart disease | Avoid prior MI/significant structural disease/HFrEF; risk 1:1 flutter; first PITP dose monitored | | **Propafenone** | Similar to flecainide | Same structural-heart-disease caution; interactions | | **Ibutilide IV** | Rapid pharmacologic conversion, especially flutter | QT prolongation/TdP; avoid significant HFrEF | | **Amiodarone IV/oral** | Useful when structural heart disease/HFrEF limits options | Slower conversion; many extracardiac toxicities | | **Procainamide IV** | Alternative conversion agent; key role in stable pre-excited AF | Hypotension, QRS/QT widening; caution HFrEF | The 2023 ACC/AHA table lists ibutilide **1 mg IV over 10 min if ≥60 kg** (0.01 mg/kg if <60 kg), with a possible second equal dose; and procainamide **1 g IV over 30 min**, followed by 2 mg/min infusion for 1 hour in studied protocols.[1] Use local drug protocols and monitoring. --- ## Anticoagulation around cardioversion: important US–European difference ### 2023 ACC/AHA/ACCP/HRS (US) For **AF duration ≥48 hours**, patients undergoing elective cardioversion should have either:[1] - **≥3 weeks uninterrupted therapeutic anticoagulation**, or - imaging (usually TEE/TOE; delayed cardiac CT can be an alternative in selected centers) excluding intracardiac thrombus. Therapeutic anticoagulation should be established before cardioversion and continued **for at least 4 weeks afterward**.[1] The guideline also notes that thromboembolic risk in AF <48 hours is not homogeneous; risk rises with patient substrate and duration, so the “48-hour rule” should not be treated as absolute biologic safety.[1] ### 2024 ESC/EACTS (Europe) ESC 2024 deliberately tightened the early-cardioversion threshold to **24 hours**. If known AF duration is **>24 hours**, early cardioversion without either ≥3 weeks therapeutic anticoagulation or TOE/TEE exclusion of thrombus is not recommended.[2,3] Most patients receive **at least 4 weeks anticoagulation after cardioversion**. ESC allows an exception in very low-risk patients with definite AF onset <24 h and no thromboembolic risk factors, but long-term anticoagulation is otherwise determined by stroke risk, not by maintenance of sinus rhythm.[2,3] #### Practical lesson When caring for a patient around 24–48 hours of known AF duration, **know your jurisdiction and local protocol**. ESC 2024 is intentionally more conservative than the traditional US 48-hour threshold. --- ## Stroke prevention ### Stroke risk is separate from rhythm strategy A patient who appears to be in sinus rhythm after cardioversion or ablation may still require long-term anticoagulation. Both major guidelines base anticoagulation on **thromboembolic risk**, not on whether the most recent ECG shows AF.[1,2] ### CHA₂DS₂-VASc (US / widely used) | Risk factor | Points | |---|---:| | Congestive heart failure/LV dysfunction | 1 | | Hypertension | 1 | | Age ≥75 years | 2 | | Diabetes mellitus | 1 | | Prior stroke/TIA/systemic embolism | 2 | | Vascular disease (MI, PAD, aortic plaque) | 1 | | Age 65–74 years | 1 | | Sex category: female | 1 | The 2023 ACC/AHA guideline recommends anticoagulation for estimated annual thromboembolic risk **≥2%**, approximately equivalent to CHA₂DS₂-VASc **≥2 in men or ≥3 in women**, and considers anticoagulation reasonable at intermediate risk (~1–2%/year; about score 1 in men or 2 in women).[1] ### CHA₂DS₂-VA (ESC 2024) ESC 2024 removes the sex-category point:[2] - **0:** generally no OAC for AF alone; - **1:** OAC should be considered; - **≥2:** OAC recommended. The goal is to simplify risk assessment and avoid using sex as a stand-alone risk factor. ### Bleeding risk Use bleeding-risk assessment to **identify modifiable risk**, not to automatically deny anticoagulation. Address: - uncontrolled hypertension; - NSAIDs/antiplatelets where avoidable; - excessive alcohol; - anemia/bleeding source; - renal/hepatic dysfunction; - labile INR on warfarin; - fall-risk contributors; - drug interactions. ESC 2024 supports HAS-BLED to flag patients needing closer review; a high score is not itself an instruction to withhold OAC.[2] --- ## Oral anticoagulants ### DOACs vs warfarin **DOACs are preferred** in most eligible AF patients because pivotal trials and meta-analyses show at least comparable efficacy with less intracranial hemorrhage than warfarin overall.[1] #### Use warfarin/VKA instead when - mechanical prosthetic heart valve; - clinically significant/rheumatic mitral stenosis (moderate–severe); - certain severe renal/hepatic situations where a DOAC is unsuitable; - cost/access/adherence considerations favor VKA; - interacting drugs make DOAC exposure unreliable. Warfarin for AF is generally targeted to **INR 2.0–3.0** unless another indication requires a different target. ### Common US-labeled DOAC doses for nonvalvular AF | DOAC | Standard dose | Common renal/clinical adjustment | Key points | |---|---|---|---| | **Apixaban** | 5 mg twice daily | 2.5 mg BID if **at least 2**: age ≥80, weight ≤60 kg, serum creatinine ≥1.5 mg/dL | Strong CYP3A4/P-gp interactions matter | | **Rivaroxaban** | 20 mg once daily **with the biggest/evening meal** | 15 mg once daily when CrCl ≤50 mL/min in US labeling | Take with food; interaction/renal review | | **Dabigatran** | 150 mg twice daily if CrCl >30 | US: 75 mg BID at CrCl 15–30; interaction-specific modifications exist | ~80% renal elimination; dyspepsia/GI bleeding considerations | | **Edoxaban** | 60 mg once daily when CrCl >50 to ≤95 | 30 mg once daily with reduced renal function (and other criteria by label) | US AF labeling avoids CrCl >95 because of reduced efficacy signal | These are **US guideline/package-label examples**.[1] European and other national labels differ—e.g., dabigatran 110 mg BID is used in selected patients outside the US, and edoxaban reduction criteria include weight and P-gp inhibitors. Always use the local product label. #### Avoid inappropriate underdosing ESC 2024 explicitly advises against reducing a DOAC dose unless the patient meets the drug-specific criteria because underdosing can produce preventable thromboembolism.[2] --- ## Antiplatelet therapy is not a substitute for anticoagulation Aspirin alone, or aspirin plus clopidogrel, is **not recommended as an alternative to OAC** for AF stroke prevention in a patient who qualifies for anticoagulation and has no separate antiplatelet indication.[1,2] For patients with AF and stable coronary disease well beyond PCI/ACS, antithrombotic regimens should be simplified according to current CAD/PCI guidance to minimize bleeding; many patients ultimately require **OAC alone** rather than indefinite OAC plus aspirin.[1] --- ## Left atrial appendage occlusion (LAAO) The 2023 US guideline gives percutaneous LAAO a stronger role:[1] - **reasonable (Class 2a)** in patients with CHA₂DS₂-VASc ≥2 who have a contraindication to long-term OAC; - **may be reasonable (Class 2b)** as an alternative in moderate–high stroke risk with high major-bleeding risk on OAC, after shared decision-making. LAAO is not “risk-free anticoagulation avoidance.” It carries procedural risks and usually requires a defined post-procedure antithrombotic regimen. #### 2025–2026 emerging evidence Recent trials continue to refine whether LAA closure can substitute for DOACs in broader populations. Some 2026 data are encouraging, whereas other high-risk studies failed noninferiority. **Current guideline-based OAC remains the standard for eligible patients**; do not generalize conference-era/device-specific results beyond their populations.[14] --- ## Long-term rate control Long-term rate control is reasonable for: - permanent AF; - minimal symptoms; - rhythm-control failure or patient preference; - patients where procedural/drug rhythm control carries unfavorable risk. #### Common agents - beta blocker; - diltiazem/verapamil when LVEF is preserved (>40% per ESC/ACC guidance); - digoxin, especially when HF/hypotension limits alternatives or as add-on therapy; - AV-node ablation with pacing in selected refractory cases. #### HFrEF Avoid diltiazem/verapamil in significant LV systolic dysfunction because of negative inotropy. Beta blockers and/or digoxin are common rate-control choices depending on decompensation, BP, and clinical context.[1,2] --- ## Long-term rhythm control: antiarrhythmic drugs Drug choice is determined by structural heart disease, coronary disease, LVEF, renal function, QT, conduction system disease, and interaction profile. | Clinical setting | Reasonable options / concepts | Avoid / caution | |---|---|---| | **No prior MI or significant structural heart disease** | Flecainide, propafenone; dronedarone; dofetilide; sotalol in selected patients | Class Ic if structural disease develops | | **HFrEF (LVEF ≤40%)** | Amiodarone or dofetilide are established US options | Flecainide/propafenone; dronedarone in recent decompensated/advanced HF; sotalol often poorly suited | | **Prior MI / significant scar** | Amiodarone, dofetilide; specialist strategy | Flecainide/propafenone (harm/proarrhythmia) | | **Marked QT prolongation / low K/Mg** | Correct factors before QT-active drugs | Dofetilide, sotalol, ibutilide without careful monitoring | | **Severe renal dysfunction** | Agent-specific specialist dosing | Dofetilide/sotalol accumulation; digoxin accumulation | ### Important drug pearls #### Flecainide / propafenone Use only when significant structural heart disease/scar/prior MI is absent. An AV-nodal blocker is often paired to prevent 1:1 conduction if atrial flutter occurs. “Pill-in-the-pocket” therapy should be restricted to carefully selected patients after a monitored first dose confirms safety.[1] #### Amiodarone Effective across a wide range of structural heart disease but carries cumulative: - thyroid toxicity; - pulmonary toxicity; - hepatic toxicity; - corneal/skin effects; - bradycardia/QT effects; - numerous drug interactions. For long-term maintenance, the 2023 ACC/AHA guideline notes low-dose **100–200 mg/day** can be effective but should generally be reserved when safer options are ineffective/not preferred because of adverse effects.[1] #### Dofetilide Effective in HFrEF but requires renal dosing and QT monitoring. In US practice, initiation/reloading requires monitored hospitalization (typically at least 3 days) because of torsades risk.[1] #### Sotalol Requires QT, renal, potassium, and magnesium monitoring. It can cause torsades and bradycardia and is often initiated under monitored conditions, especially with risk factors.[1] #### Dronedarone Can be useful in selected patients without recent decompensated HF/severe LV dysfunction. It is **harmful in NYHA III/IV HF or recent decompensated HF** and should not be used for permanent AF as a strategy to improve outcomes.[1] --- ## Catheter ablation Pulmonary vein isolation (PVI) is the cornerstone of AF catheter ablation. ### When to consider ablation - symptomatic AF despite or intolerant of antiarrhythmic drugs; - selected symptomatic paroxysmal AF as **first-line rhythm control**; - symptomatic persistent AF after drug failure, and sometimes earlier by shared decision-making; - AF with HFrEF when arrhythmia contributes to cardiomyopathy or symptoms; - recurrent AF where durable sinus rhythm is a high priority. The 2024 EHRA/HRS/APHRS/LAHRS consensus expanded first-line ablation indications and recognizes improved safety and newer technologies including pulsed-field ablation.[10] ### Outcomes: what ablation does well Ablation is superior to antiarrhythmic drug therapy for reducing recurrent AF in many selected patients and often improves symptoms and quality of life. #### CABANA In 2,204 symptomatic AF patients, ablation did **not** significantly reduce the intention-to-treat primary composite of death, disabling stroke, serious bleeding, or cardiac arrest (**8.0% vs 9.2%; HR 0.86, P=.30**), but reduced AF recurrence (**49.9% vs 69.5%; HR 0.52**) and the secondary composite of death/CV hospitalization.[15] #### CASTLE-AF In selected patients with symptomatic AF and HFrEF (LVEF ≤35%) with implanted devices, catheter ablation reduced death/HF hospitalization versus medical therapy and improved LVEF; all-cause mortality was **13.4% vs 25.0% (HR 0.53)** in the original trial report.[9] **Interpretation:** Ablation is not simply a symptom procedure in all HF patients; selected HFrEF patients can gain prognostic benefit. --- ## Anticoagulation after ablation Do not stop OAC merely because ablation “worked.” ESC 2024 recommends OAC for **at least 2 months after AF ablation in all patients**, then long-term continuation according to thromboembolic risk rather than rhythm outcome.[2] The 2023 ACC/AHA approach similarly bases long-term OAC on stroke risk rather than perceived elimination of AF.[1] #### Emerging 2026 evidence OCEAN and ALONE-AF have renewed debate about stopping anticoagulation after apparently successful ablation in carefully monitored, selected patients. However, event rates were low and trial designs have limitations. As of September 2026, **guidelines have not been replaced**: elevated-risk patients should continue OAC according to guideline risk assessment.[16] --- ## Comorbidity and risk-factor management: disease-modifying AF treatment Risk-factor treatment reduces recurrence, improves procedural success, and addresses the same substrate driving stroke/HF. ### ESC 2024 high-yield targets - treat hypertension; - optimize HF therapy; - manage diabetes; - target **≥10% body-weight reduction** in overweight/obese AF patients as part of comprehensive management; - evaluate and manage obstructive sleep apnea where appropriate; - encourage tailored exercise; - reduce alcohol to **≤3 standard drinks (≤30 g alcohol) per week** to reduce recurrence; - stop smoking.[2] The 2026 AHA/ACC performance measures explicitly make secondary prevention—weight management, physical activity, smoking cessation, alcohol moderation, and BP control—a quality focus rather than an optional lifestyle footnote.[13] --- ## Special populations and scenarios ### AF + HFrEF Priorities: - determine whether AF is causing or worsening cardiomyopathy; - avoid nondihydropyridine calcium-channel blockers when LVEF is significantly reduced; - optimize guideline-directed HF therapy; - consider early rhythm control and catheter ablation; - maintain stroke prevention according to risk. The 2023 ACC/AHA guideline gives catheter ablation a strong role in appropriate AF + HFrEF patients, supported by CASTLE-AF and subsequent evidence.[1,9] ### Hyperthyroidism Treat the thyroid disease plus rate/rhythm consequences. Beta blockade is often useful if not contraindicated. Stroke prevention still follows thromboembolic risk; do not assume AF becomes harmless simply because hyperthyroidism is reversible. ### Postoperative / “trigger-induced” AF AF during surgery, sepsis, pneumonia, or another acute trigger has a meaningful recurrence risk. The 2023 ACC/AHA guideline recommends outpatient follow-up for thromboembolic risk assessment and AF surveillance after AF identified during acute illness or surgery.[1] In sepsis-related AF, the benefit of starting anticoagulation *during the critical illness* solely for stroke prevention is uncertain; reassess after stabilization.[1] ### Pregnancy Management requires cardiology–maternal-fetal medicine coordination. Avoid DOACs because safety is not established and they are generally not recommended. Rate/rhythm drug selection and cardioversion are pregnancy-specific; electrical cardioversion can be performed when clinically necessary. Anticoagulation choice depends on gestational timing and indication, usually using heparin-based strategies and/or carefully managed VKA in selected high-risk valve situations under specialist care. ### CKD - recalculate renal function periodically; - adjust DOACs according to label and actual renal function; - avoid “set-and-forget” dosing as kidney function changes; - warfarin or apixaban may be used in selected advanced CKD/dialysis patients under guideline/shared decision-making, but evidence is less robust than in preserved renal function.[1] ### Hypertrophic cardiomyopathy / cardiac amyloidosis Stroke risk can be high independent of ordinary scores. ESC recommends OAC in AF with HCM or cardiac amyloidosis regardless of CHA₂DS₂-VA.[2] ### Athletes Assess reversible triggers, atrial remodeling, stimulant/supplement exposure, and exercise volume. Rate-control drugs may impair performance. Rhythm-control/ablation strategies may be particularly attractive after individualized electrophysiology review. --- ## Device-detected subclinical AF / atrial high-rate episodes (AHRE) This is one of the fastest-changing areas in AF medicine. ### 2023 ACC/AHA approach For patients **without a prior clinical AF diagnosis**:[1] - device-detected AHRE **5 min–24 h** with CHA₂DS₂-VASc ≥3: OAC **may be reasonable** after shared decision-making that considers episode duration and individual stroke risk; - AHRE **<5 min** with no other indication: **do not anticoagulate** solely for that episode. ### ARTESiA 4,012 patients with subclinical AF were randomized to apixaban vs aspirin. Apixaban reduced stroke/systemic embolism from **1.24% to 0.78% per patient-year (HR 0.63)** but increased major bleeding from **0.94% to 1.71% per patient-year (HR 1.80)**.[11] ### NOAH-AFNET 6 2,536 patients with AHREs were randomized to edoxaban or placebo. Edoxaban did not significantly reduce cardiovascular death/stroke/systemic embolism (**HR 0.81; P=.15**) and increased the composite of death or major bleeding (**HR 1.31**); stroke rates were low (~1%/year).[12] #### Interpretation **EMERGING EVIDENCE:** AF burden matters. A 6-minute device episode is not biologically identical to persistent clinical AF. Anticoagulation decisions for device-detected AF require shared decision-making integrating duration, stroke risk, bleeding risk, and certainty that the recorded episode is true AF. --- ## Complications ### Thromboembolic - ischemic stroke; - TIA; - systemic arterial embolism; - cognitive decline/dementia association over time. ### Cardiac - tachycardia-induced cardiomyopathy; - HF decompensation; - myocardial ischemia from supply-demand mismatch; - bradycardia/pauses due to sinus-node disease or medication; - atrial functional mitral/tricuspid regurgitation; - AF progression from paroxysmal to persistent/permanent. ### Treatment-related - anticoagulant bleeding; - antiarrhythmic proarrhythmia; - amiodarone organ toxicity; - bradycardia/AV block from rate-control therapy; - ablation complications (tamponade, vascular injury, stroke, pulmonary vein stenosis, rare atrioesophageal fistula, phrenic injury depending on technique). --- ## Monitoring and follow-up AF is dynamic; reassess periodically. ### At routine follow-up - symptoms and functional status; - rhythm/AF burden where relevant; - resting/exertional rate; - BP; - weight/obesity intervention; - alcohol/smoking/exercise; - sleep apnea management; - HF status; - anticoagulant adherence and dose appropriateness; - renal/hepatic function; - bleeding/anemia; - drug interactions; - antiarrhythmic ECG/toxicity monitoring; - changing CHA₂DS₂-VASc or CHA₂DS₂-VA risk. The **2026 AHA/ACC performance measures** specifically emphasize documenting a validated stroke/systemic-embolism risk assessment **annually** and prescribing appropriate anticoagulation.[13] --- ## Anticipating deterioration | Warning sign | Concern | Immediate action | |---|---|---| | Hypotension, pulmonary edema, ischemia with AF | AF causing instability | Synchronized cardioversion | | Very rapid irregular wide-complex rhythm | Pre-excited AF | Avoid AV-nodal blockers; cardioversion if unstable, procainamide/ibutilide if stable | | New focal neurologic deficit | AF-related stroke | Activate acute stroke pathway immediately; anticoagulation timing becomes stroke-specific | | Rising rate despite escalating blockers + sepsis/hypoxia | Compensatory tachycardia / untreated trigger | Treat underlying shock/trigger; avoid reflex drug escalation | | New LVEF reduction with high AF burden | Arrhythmia-induced cardiomyopathy | Early rhythm-control/EP evaluation | | Syncope or pauses after AF termination | Tachy-brady syndrome | Monitor; review AV nodal drugs; pacing evaluation if clinically indicated | | Bleeding on OAC | Anticoagulant complication | Stabilize, identify site, drug-specific reversal strategy if life-threatening | | Missed DOAC doses before planned cardioversion | Inadequate thrombus protection | Re-establish required anticoagulation period or use TEE/TOE-guided strategy | --- ## Common pitfalls | Pitfall | Why it is dangerous | Better approach | |---|---|---| | Treating every AF rate >120 as the primary problem | Tachycardia may be compensatory | Search for sepsis, hypovolemia, PE, hypoxia, ACS first | | Giving diltiazem/verapamil in decompensated HFrEF | Negative inotropy can worsen instability | Beta blocker only when appropriate, digoxin, amiodarone/other specialist strategy | | Giving AV-nodal blockers in pre-excited AF | Can accelerate accessory-pathway conduction → VF | Procainamide/ibutilide or cardioversion | | Using aspirin instead of anticoagulation | Inadequate AF stroke prevention | Use guideline-directed OAC when indicated | | Underdosing a DOAC “because the patient is old” | Increases preventable stroke if reduction criteria not met | Apply drug-specific label criteria | | Stopping OAC because sinus rhythm was restored | Stroke risk persists despite rhythm success | Anticoagulate by thromboembolic risk | | Assuming AF <48 h is always safe to cardiovert without anticoagulation | Risk varies by patient; ESC now uses 24 h | Follow local guideline and thromboembolic-risk strategy | | Using a bleeding score to deny OAC automatically | Withholds proven stroke prevention | Fix modifiable bleeding risks and increase follow-up | | Leaving obesity/OSA/alcohol untreated | Promotes recurrence and ablation/drug failure | Treat AF substrate with risk-factor management | | Calling post-sepsis AF “transient” and never following up | Recurrence and stroke risk can persist | Arrange surveillance and reassess OAC risk | --- ## STANDARD OF CARE vs EMERGING EVIDENCE vs EXPERIMENTAL ### STANDARD OF CARE - ECG confirmation of AF.[1,2] - Immediate synchronized cardioversion when AF causes hemodynamic instability.[1,2] - Rate control with beta blocker or diltiazem/verapamil in stable patients when LV function permits; digoxin/other agents according to context.[1] - No AV-nodal blockers in pre-excited AF.[1] - Stroke-risk assessment and guideline-directed OAC.[1,2] - DOACs preferred over warfarin except mechanical valves/significant mitral stenosis.[1,2] - Anticoagulation determined by thromboembolic risk, not apparent rhythm success.[1,2] - Risk-factor treatment (weight, BP, HF, diabetes, OSA, alcohol, exercise, smoking).[2,13] - Catheter ablation for appropriate symptomatic patients and selected AF + HFrEF populations.[1,2,10] ### EMERGING / RAPIDLY EVOLVING - Anticoagulation thresholds for **device-detected** subclinical AF after ARTESiA and NOAH-AFNET 6.[11,12] - Selective discontinuation of OAC after apparently successful ablation in carefully chosen lower-risk patients (OCEAN/ALONE-AF era); not yet a replacement for guideline risk-based anticoagulation.[16] - Pulsed-field ablation (PFA) as an increasingly used energy source with evolving comparative long-term data.[10] - Broader LAAO indications vs contemporary DOAC therapy.[14] - Wearable-derived AF burden as a risk modifier rather than binary diagnosis alone. ### EXPERIMENTAL / NOT ROUTINE - Anticoagulating every brief wearable/device-detected episode regardless of duration/risk. - Stopping anticoagulation solely because a smartwatch shows no AF after ablation. - Using AF-burden thresholds without validated clinical context to replace established stroke-risk assessment. - Novel mapping, autonomic modulation, or adjunctive ablation targets outside accepted protocols/trials. --- ## Guideline conflicts and jurisdiction differences ### 1. Stroke score - **US 2023:** validated annual risk estimate; CHA₂DS₂-VASc remains a common operational tool; female sex functions as a risk modifier in the score.[1] - **ESC 2024:** **CHA₂DS₂-VA**, removing sex category; consider OAC at 1, recommend at ≥2.[2] ### 2. Cardioversion timing - **US 2023:** ≥48 h AF → 3 weeks therapeutic anticoagulation or imaging before elective cardioversion; continue ≥4 weeks afterward.[1] - **ESC 2024:** >24 h known AF duration → do not perform early cardioversion without 3 weeks anticoagulation or TOE exclusion; most receive ≥4 weeks afterward.[2,3] ### 3. DOAC dosing Renal thresholds and approved lower doses differ by FDA, EMA, MHRA, and national labels. **Never transplant a US dose table into another jurisdiction without checking the local label.** --- ## Landmark and practice-shaping evidence ### EAST-AFNET 4 — early rhythm control (2020) - 2,789 patients with early AF and cardiovascular conditions. - Median time from AF diagnosis: 36 days. - Primary outcome: CV death, stroke, hospitalization for HF or ACS. - **3.9 vs 5.0 events/100 person-years; HR 0.79; P=.005** for early rhythm control vs usual care.[8] **Takeaway:** Selected early AF deserves proactive rhythm-control discussion even when symptoms are modest. ### CASTLE-AF — ablation in HFrEF (2018) Selected symptomatic AF patients with LVEF ≤35% and implanted devices had lower death/HF hospitalization with catheter ablation; all-cause mortality was **13.4% vs 25.0%; HR 0.53**.[9] **Takeaway:** In appropriate HFrEF, ablation can be prognostic therapy, not merely symptom therapy. ### CABANA — ablation vs drug strategy (2019) Ablation did not significantly reduce the primary intention-to-treat hard-event composite (**8.0% vs 9.2%, HR 0.86**) but substantially reduced AF recurrence and CV hospitalization-related secondary outcomes.[15] **Takeaway:** Ablation reliably improves rhythm control; interpretation of hard outcomes is influenced by crossover and patient selection. ### ARTESiA — device-detected AF (2024) Apixaban reduced stroke/systemic embolism (**0.78% vs 1.24%/year; HR 0.63**) but increased major bleeding (**1.71% vs 0.94%/year; HR 1.80**).[11] ### NOAH-AFNET 6 — AHRE (2023) Edoxaban did not significantly reduce the primary efficacy composite (**HR 0.81; P=.15**) and increased death/major-bleeding composite (**HR 1.31**).[12] **Takeaway:** Subclinical AF anticoagulation requires individualized net-benefit analysis. --- ## Exam-focused review ### USMLE Step 1 Know: - chaotic atrial depolarization → no organized P waves; - variable AV conduction → irregularly irregular ventricular rhythm; - loss of atrial kick is especially important in diastolic dysfunction; - LAA stasis → embolic stroke; - pulmonary veins are common AF triggers; - chronic AF causes electrical/structural remodeling. ### USMLE Step 2 CK Prioritize: - unstable AF → synchronized cardioversion; - stable RVR → rate control *after* assessing trigger and EF; - pre-excited AF → **no AV-nodal blockers**; - anticoagulation by stroke risk; - cardioversion anticoagulation based on duration/risk; - thyroid/electrolyte/structural evaluation in new AF. ### Step 3 / Resident Focus on: - anticoagulant dose/renal interactions; - distinguishing compensatory tachycardia from primary RVR; - when early rhythm control is prognostic; - post-ablation anticoagulation; - HFrEF-specific drug choices; - peri-cardioversion anticoagulation. ### MRCP / ABIM / Boards High-yield traps: - female sex alone does not mandate OAC; ESC removed sex from its score. - aspirin is not a substitute for OAC. - normal sinus rhythm after ablation does not automatically permit stopping OAC. - diltiazem/verapamil are inappropriate in significant HFrEF. - amiodarone is **also** an AV-nodal-blocking danger in pre-excited AF according to the 2023 US guideline. - device-detected AF has a different evidence base from clinical AF. - ESC 2024 uses a 24-hour early-cardioversion threshold; US 2023 retains the ≥48-hour Class I trigger for mandatory 3-week anticoagulation/imaging. --- ## Original MCQs ### Question 1 A 68-year-old man with AF presents with BP 72/40 mmHg, acute pulmonary edema, and a ventricular rate of 170/min. What is the next best step? A. Oral metoprolol B. IV digoxin and reassess in 6 hours C. Synchronized electrical cardioversion D. Start apixaban and wait 3 weeks E. TEE before any intervention **Answer: C.** AF is causing hemodynamic instability. Immediate synchronized cardioversion takes priority; anticoagulation is addressed as soon as safely feasible.[1,2] --- ### Question 2 A 28-year-old with known WPW presents with a very rapid irregular wide-complex tachycardia and stable blood pressure. Which is the most appropriate pharmacologic option? A. Adenosine B. Diltiazem C. Digoxin D. IV procainamide E. IV amiodarone **Answer: D.** Stable pre-excited AF can be treated with IV procainamide or ibutilide. AV-nodal blockers—including amiodarone in this setting—are contraindicated because they can precipitate VF.[1] --- ### Question 3 A 78-year-old woman with hypertension, diabetes, and paroxysmal AF is in sinus rhythm after successful ablation. She asks to stop anticoagulation because her smartwatch has shown no AF for 9 months. Which is most accurate? A. Anticoagulation is unnecessary if AF is not currently visible B. Ablation eliminates stroke risk completely C. Long-term anticoagulation should be based on thromboembolic risk, not perceived rhythm success D. Aspirin is equivalent to a DOAC after ablation E. Anticoagulation is required for only 24 hours after ablation **Answer: C.** Current ACC and ESC guidelines base long-term OAC on stroke risk. ESC requires OAC for at least 2 months after ablation in all patients, then continued according to risk.[1,2] --- ### Question 4 A patient with stable AF with RVR has an LVEF of 25% and acute decompensated heart failure. Which rate-control drug is least appropriate? A. Digoxin B. Carefully selected beta-blocker strategy after stabilization C. Diltiazem D. IV amiodarone in selected critically ill patients E. Specialist rhythm-control evaluation **Answer: C.** Diltiazem/verapamil should be avoided in significant HFrEF because of negative inotropy.[1,2] --- ### Question 5 A hemodynamically stable patient in Europe has definite AF onset 30 hours ago, has not been anticoagulated, and is being considered for elective cardioversion. According to ESC 2024, what is the safest guideline-consistent approach? A. Cardioversion without anticoagulation because AF is <48 h B. Proceed only after ≥3 weeks therapeutic anticoagulation or TOE/TEE exclusion of thrombus C. Aspirin for one dose before cardioversion D. Cardioversion and no postprocedure anticoagulation in all cases E. Anticoagulation is never needed if CHA₂DS₂-VA is 0 **Answer: B.** ESC 2024 reduced the un-anticoagulated early-cardioversion threshold from 48 to 24 hours.[2,3] --- ### Question 6 A pacemaker detects recurrent 1-hour AHRE episodes in a 77-year-old with hypertension and prior TIA, but no clinical AF on surface ECG. Which statement best reflects current evidence? A. All AHREs require anticoagulation regardless of duration/risk B. AHREs never carry stroke risk C. Anticoagulation should be individualized because ARTESiA showed fewer embolic events but more major bleeding, while NOAH-AFNET 6 showed no significant primary efficacy benefit and more safety events D. Aspirin is proven superior to apixaban E. The device should be ignored **Answer: C.** Device-detected AF/AHRE requires confirmation and net-benefit assessment rather than automatic treatment.[11,12] --- ### Question 7 A 64-year-old with recently diagnosed AF, hypertension, diabetes, and mild symptoms asks whether rhythm control is only for symptom relief. Which trial most directly changed this concept? A. RACE II B. EAST-AFNET 4 C. RE-LY D. ROCKET-AF E. AFFIRM only **Answer: B.** EAST-AFNET 4 showed early rhythm control reduced a composite of CV death, stroke, and HF/ACS hospitalization in selected patients with early AF and cardiovascular conditions.[8] --- ## Acute management checklist ### Recognition - [ ] Confirm AF on ECG. - [ ] Determine hemodynamic stability. - [ ] Look for pre-excitation / wide irregular tachycardia. - [ ] Estimate episode duration. - [ ] Identify anticoagulant use/adherence and last dose. ### Unstable - [ ] Synchronized electrical cardioversion. - [ ] Resuscitation/oxygenation as needed. - [ ] Anticoagulate as soon as clinically safe. - [ ] Treat precipitant (ACS, sepsis, PE, hypoxia, etc.). ### Stable RVR - [ ] Treat trigger first/alongside rate control. - [ ] Check LVEF/HF status before diltiazem/verapamil. - [ ] Beta blocker or nondihydropyridine CCB if appropriate. - [ ] Consider digoxin / magnesium / amiodarone in selected contexts. - [ ] Reassess BP, symptoms, rate, perfusion. ### Cardioversion planning - [ ] Verify AF duration and jurisdictional threshold. - [ ] US: ≥48 h → ≥3 wk OAC or imaging before elective cardioversion. - [ ] ESC: >24 h → ≥3 wk OAC or TOE before early cardioversion. - [ ] Continue OAC ≥4 wk after cardioversion in most patients/according to guideline. - [ ] Decide long-term OAC by stroke risk, not sinus rhythm. ### Long-term AF-CARE - [ ] **C:** BP, weight, HF, diabetes, OSA, alcohol, smoking, exercise. - [ ] **A:** annual stroke-risk reassessment; correct DOAC dose/adherence. - [ ] **R:** rate vs early rhythm control; consider ablation. - [ ] **E:** reassess symptoms, AF burden, renal function, bleeding, HF, evolving risks. --- ## References 1. **Joglar JA, Chung MK, Armbruster AL, et al.** 2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation. *Circulation.* 2024;149:e1-e156 / *J Am Coll Cardiol.* 2024;83:109-279. doi: **10.1016/j.jacc.2023.08.017**. Official ACC guideline: https://www.acc.org/Guidelines/Guidelines/2023/11/30/12/05/Atrial-Fibrillation-2023-Guideline 2. **Van Gelder IC, Rienstra M, Bunting KV, et al.; ESC Scientific Document Group.** 2024 ESC Guidelines for the management of atrial fibrillation developed in collaboration with EACTS. *Eur Heart J.* 2024;45:3314-3414. doi: **10.1093/eurheartj/ehae176**. https://www.escardio.org/guidelines/clinical-practice-guidelines/all-esc-practice-guidelines/atrial-fibrillation/ 3. **Kotecha D, et al.** Spotlight on the 2024 ESC/EACTS management of atrial fibrillation guidelines: 10 novel key aspects. *Europace.* 2025. PMID: **39716733**. 4. **Hindricks G, Potpara T, Dagres N, et al.** 2020 ESC Guidelines for the diagnosis and management of atrial fibrillation. *Eur Heart J.* 2021;42:373-498. doi:10.1093/eurheartj/ehaa612. (Historical comparator for changed recommendations.) 5. **Kirchhof P, Benussi S, Kotecha D, et al.** 2016 ESC Guidelines for the management of atrial fibrillation. *Eur Heart J.* 2016;37:2893-2962. doi:10.1093/eurheartj/ehw210. (Historical framework.) 6. **Van Gelder IC, Groenveld HF, Crijns HJGM, et al.; RACE II Investigators.** Lenient versus strict rate control in patients with atrial fibrillation. *N Engl J Med.* 2010;362:1363-1373. doi: **10.1056/NEJMoa1001337**. 7. **Al-Khatib SM, et al.** Contemporary evidence for pharmacological rate and rhythm control is incorporated in the 2023 ACC/AHA/ACCP/HRS guideline; use the guideline drug tables and local labeling for prescribing.[1] 8. **Kirchhof P, Camm AJ, Goette A, et al.; EAST-AFNET 4 Trial Investigators.** Early Rhythm-Control Therapy in Patients with Atrial Fibrillation. *N Engl J Med.* 2020;383:1305-1316. doi: **10.1056/NEJMoa2019422**. 9. **Marrouche NF, Brachmann J, Andresen D, et al.; CASTLE-AF Investigators.** Catheter Ablation for Atrial Fibrillation with Heart Failure. *N Engl J Med.* 2018;378:417-427. doi: **10.1056/NEJMoa1707855**. 10. **Tzeis S, et al.** 2024 EHRA/HRS/APHRS/LAHRS Expert Consensus Statement on Catheter and Surgical Ablation of Atrial Fibrillation. Endorsed by HRS, EHRA, APHRS, LAHRS. https://www.hrsonline.org/resource/2024-ehra-hrs-aphrs-lahrs-expert-consensus-statement-on-catheter-and-surgical-ablation-of-atrial-fibrillation/ 11. **Healey JS, Lopes RD, Granger CB, et al.; ARTESiA Investigators.** Apixaban for Stroke Prevention in Subclinical Atrial Fibrillation. *N Engl J Med.* 2024;390:107-117. doi: **10.1056/NEJMoa2310234**. PMID: **37952132**. 12. **Kirchhof P, Toennis T, Goette A, et al.; NOAH-AFNET 6 Investigators.** Anticoagulation with Edoxaban in Patients with Atrial High-Rate Episodes. *N Engl J Med.* 2023;389:1167-1179. doi: **10.1056/NEJMoa2303062**. 13. **Benjamin EJ, Marcus GM, Hess PL, et al.** 2026 AHA/ACC Clinical Performance and Quality Measures for Patients With Atrial Fibrillation. Published online August 17, 2026. *Circ Cardiovasc Qual Outcomes.* doi: **10.1161/HCQ.0000000000000149**; parallel JACC publication doi: **10.1016/j.jacc.2026.05.032**. https://professional.heart.org/en/science-news/2026-clinical-performance-and-quality-measures-for-patients-with-atrial-fibrillation 14. **ACC 2025–2026 LAAO trial reporting.** Contemporary LAA-closure evidence remains heterogeneous; current anticoagulation recommendations should not be displaced by individual new device trials without guideline integration. ACC Clinical Trials / Scientific Sessions 2025–2026. 15. **Packer DL, Mark DB, Robb RA, et al.; CABANA Investigators.** Effect of Catheter Ablation vs Antiarrhythmic Drug Therapy on Mortality, Stroke, Bleeding, and Cardiac Arrest Among Patients With Atrial Fibrillation. *JAMA.* 2019;321:1261-1274. doi: **10.1001/jama.2019.0693**. PMID: **30874766**. 16. **American College of Cardiology.** Discontinuation of Anticoagulation Following Catheter Ablation of AF: Updates With OCEAN Trial. July 1, 2026. Current guidelines still base long-term OAC on thromboembolic risk. https://www.acc.org/Latest-in-Cardiology/Articles/2026/06/29/15/28/Discontinuation-of-Anticoagulation --- ### NEXT-TOPIC LEDGER **Completed today:** Atrial Fibrillation **Do not repeat normalized title:** `atrial-fibrillation` **Suggested future linked topics:** Atrial flutter; Supraventricular tachycardia; Anticoagulation in AF; Cardioversion; Catheter ablation for AF; Bradyarrhythmias and tachy-brady syndrome; Wolff-Parkinson-White syndrome; Heart failure with atrial fibrillation1b: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.1c:T7b05,## One-minute summary **Acute bacterial meningitis** is infection-driven inflammation of the leptomeninges and cerebrospinal fluid (CSF). It can progress over hours to **sepsis, shock, cerebral edema, seizures, raised intracranial pressure, herniation, hearing loss, neurologic disability, and death**. WHO's first global meningitis diagnosis/treatment guideline was released in 2025, followed by a practical implementation manual in May 2026.[1,2] WHO estimates bacterial meningitis causes death in roughly **1 in 6 affected people**, and about **1 in 5 survivors** develops long-term complications.[1] ### The core emergency sequence 1. **Recognize the syndrome**: fever, headache, neck stiffness, altered mental status, photophobia, vomiting, seizure, focal deficit, non-blanching rash, or sepsis; not every patient has the classic triad. 2. **Stabilize ABCs** and treat shock/seizures immediately. 3. Obtain **blood cultures and key blood tests**, but never allow diagnostics to cause a clinically significant antibiotic delay. 4. Perform **lumbar puncture before antibiotics if safe and immediately feasible**. 5. **Do not routinely obtain CT before LP.** Image first only when specific features suggest a space-occupying lesion or dangerous raised intracranial pressure. 6. Start **IV antibiotics as soon as meningitis is suspected**; NICE specifies within **1 hour of hospital arrival**.[3] 7. Give **IV dexamethasone with or before the first antibiotic dose if possible** in strongly suspected bacterial meningitis (age >3 months in NICE guidance); never delay antibiotics for dexamethasone.[3] 8. Narrow therapy once Gram stain, PCR, culture, and susceptibility data return. 9. Assess for **hearing and neurologic sequelae** and involve public health for meningococcal disease. ★ **High-yield principle:** If CT is needed before LP, **take bloods and start antibiotics first**. Imaging must not become a treatment-delay ritual.[3] --- ## Definition Meningitis is inflammation of the meninges and CSF, usually infectious. **Bacterial meningitis** refers to acute meningitis caused by bacteria, most often acquired in the community but sometimes related to neurosurgery, skull defects, penetrating trauma, CSF devices, or bacteremia. This article focuses primarily on **acute community-acquired bacterial meningitis in children beyond the neonatal period and adults**, with emphasis on adult clinical reasoning. Neonatal, post-neurosurgical, TB, cryptococcal, and chronic meningitis require specialized protocols. --- ## Epidemiology and major pathogens The pathogen distribution varies with age, vaccination, immune status, geography, and healthcare exposure. | Population / risk state | Important organisms | Practical implication | |---|---|---| | Adolescents / younger adults | *Neisseria meningitidis*, *Streptococcus pneumoniae* | Consider meningococcal sepsis/rash; droplet precautions and public-health actions | | General adults | *S. pneumoniae*, *N. meningitidis* | Pneumococcus is a major cause of severe adult disease | | Older adults / cell-mediated immune impairment | Above + *Listeria monocytogenes* | Add anti-Listeria therapy | | Asplenia / complement deficiency | Encapsulated organisms, especially meningococcus/pneumococcus | Higher invasive-disease risk | | Cochlear implant / CSF leak | Pneumococcus | Recurrent meningitis risk; vaccination/prevention critical | | Neurosurgery / CSF shunt | Staphylococci, resistant gram-negative bacilli | Not a standard community-acquired regimen; use healthcare-associated CNS infection guidance | #### Risk factors - Extremes of age - Asplenia or hyposplenia - Complement deficiency or complement-inhibitor therapy - HIV or other immunocompromise - Alcohol use disorder - Diabetes and chronic disease - Otitis, mastoiditis, sinusitis, pneumonia - Basilar skull fracture or CSF leak - Cochlear implant - Recent neurosurgery or CSF device - Crowded living environments for meningococcal transmission - Under-immunization --- ## Pathophysiology The disease usually follows: **nasopharyngeal colonization or local infection → mucosal invasion/bacteremia → crossing of the blood–brain/CSF barriers → bacterial replication in CSF → intense host inflammatory response → endothelial injury and blood–brain barrier disruption → vasogenic/cytotoxic/interstitial edema + impaired CSF flow + vasculitis/thrombosis → increased intracranial pressure and reduced cerebral perfusion.** Bacterial cell-wall products trigger cytokines and neutrophilic inflammation. Complications arise not only from bacterial burden but also from the inflammatory response, which is why appropriately timed corticosteroids can reduce selected neurologic sequelae. --- ## Clinical presentation ### Classic adult features - Fever - Severe headache - Neck stiffness - Altered mental status - Photophobia - Nausea/vomiting The “classic triad” of fever, neck stiffness, and altered consciousness is **not sensitive enough to rule out disease when incomplete**. #### Additional features - Seizure - Focal neurologic deficit - Cranial nerve palsy - Reduced GCS - Petechial or purpuric rash - Shock/DIC - Limb pain or rapidly progressive sepsis in meningococcal disease #### Infants and children Presentation may be nonspecific: irritability, poor feeding, lethargy, high-pitched cry, fever or hypothermia, vomiting, seizures, bulging fontanelle, abnormal tone. #### Older or immunocompromised adults Fever and meningeal signs may be muted. New delirium, sepsis, seizure, or unexplained decline may dominate. --- ## Red flags requiring immediate resuscitation / ICU-level concern - GCS ≤9 or rapidly declining consciousness - Recurrent/prolonged seizure - Abnormal pupils or posturing - Focal neurologic deficit - Shock, rising lactate, DIC - Purpura fulminans / rapidly spreading non-blanching rash - Respiratory failure - Signs of impending herniation - Severe hyponatremia or other metabolic complication --- ## Initial assessment and “what to do next” | Component | Assessment | Interpretation | Immediate action | Anticipate deterioration | |---|---|---|---|---| | A — Airway | GCS, protective reflexes, vomiting | Airway loss risk | Airway support/intubation when indicated | Aspiration, herniation physiology | | B — Breathing | RR, SpO₂, work of breathing | Sepsis, aspiration, pulmonary complication | Oxygen/ventilation as needed | Fatigue, ARDS | | C — Circulation | HR, BP, perfusion, rash, lactate | Septic shock/DIC | IV/IO access, sepsis resuscitation | Refractory shock, adrenal hemorrhage | | D — Disability | GCS, pupils, focal deficit, seizure, glucose | Raised ICP, stroke mimic, hypoglycemia | Treat seizure/glucose; decide LP safety | Herniation, status epilepticus | | E — Exposure | Rash, infection source, trauma/CSF leak | Meningococcus, source clue | Droplet precautions if suspected meningococcus; source management | Rapid purpura/DIC | --- ## Diagnostic strategy ### Blood tests before antibiotics when feasible NICE recommends the following in suspected bacterial meningitis:[3] - Blood culture - WBC with neutrophils - CRP, or procalcitonin if CRP unavailable - Blood glucose - Whole-blood diagnostic PCR including meningococcal and pneumococcal targets where available - HIV testing according to local policy Do **not** rule out meningitis because WBC, CRP, or procalcitonin is normal.[3] Additional tests often include electrolytes, renal/liver profile, lactate, coagulation studies, and type/screen if severe DIC or critical illness is present. --- ## Lumbar puncture: do it early, but safely NICE states that LP should be performed before antibiotics **unless it is unsafe or would cause a clinically significant delay**. If antibiotics have already been started, perform LP as soon as safely possible.[3] ### Stabilize before LP Treat/stabilize these first:[3] - Unprotected airway - Respiratory compromise - Shock - Uncontrolled seizures - Bleeding risk ### Do not perform immediate LP when there is - Extensive/rapidly spreading purpura - Infection at the LP site - Risk factors for an evolving intracranial space-occupying lesion - Clinical signs suggesting dangerous raised ICP requiring imaging first --- ## CT before lumbar puncture: NOT routine NICE explicitly advises **against routine neuroimaging before LP**.[3,4] #### Image before LP when there is - Risk of an evolving space-occupying lesion - New focal neurologic features, including seizure or posturing - Abnormal pupillary reactions - **GCS ≤9** - Progressive sustained or rapid fall in consciousness[3] #### Critical sequence when imaging is required **Bloods → antibiotics (and dexamethasone when indicated) → stabilization → neuroimaging → LP when safe.** ⚠ **Common trap:** “Possible meningitis = CT first.” This delays antibiotics and is not recommended for most patients. --- ## CSF investigations NICE recommends:[3] - RBC and WBC count with differential - Total protein - CSF glucose **with paired blood glucose** to calculate CSF:blood glucose ratio - Gram stain - Culture and antimicrobial susceptibility - PCR for relevant pathogens Store remaining CSF for additional testing if needed.[3] ### Typical CSF patterns | Feature | Bacterial | Viral | TB/fungal (typical) | |---|---|---|---| | Opening pressure | Often high | Normal or mildly high | Often high | | WBC | High, usually neutrophilic | Lymphocytic | Lymphocytic/mononuclear | | Protein | High | Mild–moderately high | High | | Glucose | Low | Usually normal | Low | | CSF:blood glucose ratio | Reduced | Usually preserved | Reduced | | Gram stain/culture | May identify organism | Negative for bacteria | Specialized stains/culture/PCR | **Exceptions are common.** Early bacterial disease can be less neutrophilic; partially treated bacterial meningitis can have altered CSF findings; immunocompromised patients can have weak pleocytosis. --- ## Empiric antibiotics ### STANDARD OF CARE: treatment must not wait NICE recommends IV antibiotics as soon as bacterial meningitis is suspected, **within 1 hour of hospital arrival**.[3] #### UK/NICE approach Before the organism is known:[3] - **Ceftriaxone** at the highest meningitis dose recommended by formulary/local guidance - If ceftriaxone is contraindicated, consider **cefotaxime** - Add **IV amoxicillin** when there are risk factors for *Listeria monocytogenes* NICE does **not** recommend routine aciclovir unless herpes simplex encephalitis is strongly suspected.[3] #### Common adult meningitis doses used internationally These are common adult regimens; always verify local guidance, renal function, body size, allergy and resistance patterns: | Drug | Common adult meningitis dosing | Role | |---|---:|---| | Ceftriaxone | **2 g IV every 12 h** (or total 4 g/day in some protocols) | Core empiric agent / pneumococcus, meningococcus, Hib coverage | | Ampicillin / amoxicillin | **2 g IV every 4 h** (local protocols may vary) | *Listeria* coverage | | Vancomycin | Weight- and renal-function based; dose/monitor to local AUC or trough protocol | Added in many North American regimens for resistant pneumococcus | | Dexamethasone | **10 mg IV every 6 h** in adults | Adjunct, ideally before/with first antibiotic | #### U.S./North American vs UK/WHO nuance Many North American empiric adult protocols use **vancomycin + a third-generation cephalosporin**, adding ampicillin when Listeria risk is present because of concern for cephalosporin-resistant pneumococci. NICE uses ceftriaxone (or cefotaxime) as its core empiric regimen and recommends specialist input for resistance risks.[3] **Do not blindly merge regimens.** Use the guideline adopted in your jurisdiction and local pneumococcal susceptibility data. --- ## Dexamethasone NICE recommends IV dexamethasone for people **over 3 months** with strongly suspected or confirmed bacterial meningitis.[3] #### Timing - Give **with or before the first antibiotic dose if possible**. - Do **not** delay antibiotics to administer dexamethasone. - If delayed by <12 hours after antibiotics, NICE advises giving it as soon as possible; if >12 hours late, obtain infection-specialist advice.[3] #### Adult dose A widely used adult regimen, supported by the landmark randomized trial and common clinical guidance, is **dexamethasone 10 mg IV every 6 hours for 4 days**.[5] #### Continue or stop when organism known NICE recommends:[3] - **Continue** if *S. pneumoniae* or *H. influenzae* type b - **Stop** for other identified organisms - If no organism is identified, seek infection-specialist advice #### Why timing matters Antibiotic-induced bacterial lysis can amplify meningeal inflammation. Steroids are most useful when present before or at the onset of this inflammatory burst. --- ## Pathogen-specific treatment and duration Exact definitive therapy depends on susceptibility and jurisdiction. | Organism | Typical targeted approach | NICE duration concept | |---|---|---| | *N. meningitidis* | Ceftriaxone/cefotaxime; penicillin/ampicillin if susceptibility proven in some systems | **5 days** if recovered[3] | | *S. pneumoniae* | Ceftriaxone/cefotaxime ± vancomycin depending susceptibility/local resistance | **10 days** if recovered[3] | | Hib | Ceftriaxone/cefotaxime | **7 days**, extend to 10 if not recovered[3] | | Group B streptococcus | Ceftriaxone/cefotaxime; specialist input | **14 days** if recovered[3] | | *Listeria monocytogenes* | Ampicillin/amoxicillin-based therapy; specialist guidance | Often prolonged, commonly ~21 days depending disease/response | | Gram-negative bacilli | Susceptibility-guided 3rd/4th-gen cephalosporin or other agent | Often ~21 days; specialist management | NICE states that when CSF suggests bacterial meningitis but blood culture/PCR are negative, initial antibiotics can be continued for **10 days**, stopping if recovered or seeking specialist advice if not.[3] --- ## Meningococcal disease Meningococcal infection may present as meningitis, meningococcemia, or both. ### Clues - Rapidly progressive sepsis - Petechiae/purpura - Limb pain - Shock - DIC - Meningism may be absent in bloodstream-predominant disease #### Infection control Use appropriate **droplet precautions** for suspected meningococcal disease according to local infection-prevention policy. #### Treatment CDC guidance updated in 2026 states empiric treatment should include an extended-spectrum cephalosporin such as **ceftriaxone or cefotaxime**. Once susceptibility is known, penicillin or ampicillin may be used when susceptible.[6] #### Public-health actions Urgently notify public health according to jurisdiction. Close contacts may require chemoprophylaxis, and vaccination may be required depending on serogroup/outbreak context. ★ **Important:** Ceftriaxone treatment effectively clears carriage after a dose; if treatment used cefotaxime or penicillin/ampicillin, additional eradication therapy may be required before discharge according to CDC guidance.[6] --- ## Supportive and critical care ### Sepsis / shock Treat according to current sepsis principles: - Rapid IV/IO access - Lactate when indicated - Appropriate fluids with repeated reassessment - Norepinephrine for persistent vasodilatory shock when indicated - Source-directed antimicrobial therapy - Organ support ### Fluids NICE advises **not routinely restricting fluids below maintenance needs** in bacterial meningitis.[3] ⚠ **Common trap:** Historic reflex fluid restriction can worsen perfusion. Correct true SIADH/hyponatremia thoughtfully, but do not impose routine dehydration. ### Intracranial pressure NICE advises against routine glycerol and against routine use of osmotic agents such as mannitol or hypertonic saline for all meningitis patients.[3] Osmotherapy is reserved for selected patients with suspected impending herniation/raised ICP under critical-care/neurospecialist guidance. General neuroprotective principles include: - Avoid hypoxemia - Avoid hypotension - Treat fever and seizures - Elevate head of bed in selected patients - Maintain appropriate ventilation; avoid unnecessary prolonged hyperventilation - Urgent neurocritical care when herniation is suspected ### Seizures Treat status epilepticus promptly with standard protocols. Persistent altered consciousness may require EEG to detect nonconvulsive seizures. --- ## Complications ### Acute neurologic - Raised ICP / cerebral edema - Brain herniation - Seizures/status epilepticus - Ischemic stroke from vasculitis/thrombosis - Cerebral venous thrombosis - Hydrocephalus - Subdural effusion/empyema - Cranial neuropathies ### Systemic - Septic shock - DIC - Purpura fulminans - Acute kidney injury - ARDS - Waterhouse–Friderichsen syndrome in fulminant meningococcemia ### Long-term WHO highlights long-term complications in approximately **20%** of bacterial meningitis survivors.[1] Important sequelae: - Sensorineural hearing loss - Cognitive impairment - Epilepsy - Motor deficits - Visual/cranial nerve deficits - Learning/behavioral problems in children - Psychological sequelae and reduced quality of life --- ## Hearing and follow-up All survivors require structured assessment for neurologic and functional sequelae. Hearing evaluation is especially important after pneumococcal/Hib disease and in children, because hearing loss can be clinically silent initially but profoundly affect development. Follow-up should address: - Audiology - Cognitive and neurologic function - Seizure recurrence - Rehabilitation needs - Vaccination status - Evaluation for predisposing CSF leak, asplenia, complement deficiency, cochlear implant issues, or immune deficiency when clinically indicated --- ## Prevention ### Vaccination Major prevention tools include: - Pneumococcal vaccination - Hib vaccination - Meningococcal ACWY vaccination - Meningococcal B vaccination in indicated populations Schedules vary by age, country, risk group, and evolving public-health recommendations. ### Meningococcal contact prophylaxis Close contacts and people exposed directly to oral/respiratory secretions can require antibiotic prophylaxis. CDC options include rifampin, ciprofloxacin, or ceftriaxone, with selection based on age, pregnancy, resistance, and local public-health advice.[6] --- ## Special populations ### Immunocompromised / older adult Have a lower threshold for *Listeria* coverage and for atypical presentation. Consider broader differential: cryptococcal, TB, fungal, viral, malignant, and drug-related meningitis. ### Pregnancy *Listeria* risk is important. Antibiotic and prophylaxis choices should be coordinated with infectious disease and obstetrics. ### Asplenia / complement inhibitor therapy High risk of invasive encapsulated organisms. Prevention with vaccination and education about urgent fever management is essential. ### Cochlear implants / CSF leak Recurrent pneumococcal meningitis risk may be elevated. Investigate anatomical predisposition and ensure appropriate vaccination. ### Neurosurgical patients Do not use a routine community-acquired pathway. Post-craniotomy, shunts, drains, and penetrating trauma raise concern for staphylococci and resistant gram-negative bacilli; use healthcare-associated ventriculitis/meningitis guidance. --- ## Important mimics and alternative diagnoses | Condition | Clues | Key discriminator | |---|---|---| | Viral meningitis | Often less toxic, normal glucose | PCR; clinical course | | HSV encephalitis | Altered behavior, focal seizures, temporal signs | Brain MRI + CSF HSV PCR; empiric aciclovir when strongly suspected | | TB meningitis | Subacute course, cranial neuropathies, low glucose | TB testing, imaging, epidemiology | | Cryptococcal meningitis | HIV/immunocompromise, high opening pressure | CSF cryptococcal antigen | | Subarachnoid hemorrhage | Thunderclap headache | CT ± LP for blood/xanthochromia | | Brain abscess | Focal deficit, seizures, source infection | MRI/CT; LP may be unsafe/unhelpful | | Autoimmune encephalitis | Psychiatric symptoms, seizures, dyskinesia | CSF/serology/EEG/MRI | | Drug-induced aseptic meningitis | Temporal medication relationship | Exclusion + history | --- ## Diagnostic / management algorithm ```text Fever/headache/neck stiffness/AMS/seizure/rash → suspect meningitis ↓ ABC stabilization ↓ Blood cultures + CBC/CRP(or PCT) + glucose + chemistries ± PCR ↓ Is immediate LP safe, and can it occur without significant antibiotic delay? ├── YES → LP: cells/diff, protein, CSF glucose + paired blood glucose, │ Gram stain, culture/susceptibility, PCR │ ↓ │ IV antibiotics immediately + dexamethasone with/before first dose │ └── NO → IV antibiotics immediately + dexamethasone when indicated ↓ Does patient meet imaging-before-LP criteria? ├── YES → stabilize + CT/MRI → LP when safe └── NO → LP as soon as safely feasible Then: Gram stain/PCR/culture + susceptibility → narrow therapy Assess seizures/ICP/shock continuously Meningococcus? → droplet precautions + public health + contact management Recovery → hearing + neurologic follow-up + prevention evaluation ``` --- ## Acute management checklist - [ ] ABCs; treat hypoxemia, shock, uncontrolled seizures - [ ] Droplet precautions if meningococcal disease suspected - [ ] Blood cultures before antibiotics if this does not delay therapy - [ ] CBC, CRP/PCT, blood glucose, chemistries; lactate/coagulation if ill - [ ] LP immediately if safe and feasible - [ ] **No routine CT before LP** - [ ] If focal signs, abnormal pupils, GCS ≤9, rapid consciousness decline, or mass-lesion risk → image first, but **antibiotics first** - [ ] IV ceftriaxone-based empiric therapy per local guideline - [ ] Add Listeria coverage when risk factors present - [ ] Add vancomycin when required by local pneumococcal-resistance policy (common North American practice) - [ ] Dexamethasone with/before first antibiotic dose if indicated; never delay antibiotics - [ ] CSF cell count/diff, protein, glucose + paired serum glucose, Gram stain, culture, PCR - [ ] Narrow regimen and define duration once organism/susceptibility known - [ ] Monitor sodium, renal function, neurologic status, seizures, perfusion - [ ] Public-health notification/contact prophylaxis if meningococcus - [ ] Arrange hearing and neurologic follow-up --- ## Common pitfalls | Pitfall | Why dangerous | Better approach | |---|---|---| | Waiting for the classic triad | Triad is insensitive | Use overall syndrome and risk state | | CT on every suspected case | Delays LP and antibiotics | CT only for defined risk features | | Delaying antibiotics until after imaging/LP | Mortality/neurologic harm | Treat within 1 hour; diagnostics only if they do not delay | | Normal CRP/WBC “rules out” disease | False reassurance | NICE explicitly warns against this | | No paired serum glucose with CSF | Loses useful CSF:blood ratio | Draw blood glucose with LP | | Forgetting Listeria in older/immunocompromised patient | Cephalosporins do not reliably cover Listeria | Add ampicillin/amoxicillin when risk present | | Routine aciclovir for all meningitis | Unnecessary treatment | Use when HSV encephalitis is strongly suspected | | Giving dexamethasone hours later without thought | Benefit depends on timing/pathogen | Give with/before antibiotics; follow guideline if delayed | | Routine fluid restriction | May worsen perfusion | Maintain appropriate fluids; treat specific sodium disorder | | Missing meningococcal public-health actions | Preventable secondary cases | Isolation + urgent notification + contact prophylaxis | --- ## Current guideline changes ### WHO 2025 guideline + 2026 practical manual WHO issued its **first global guideline on meningitis diagnosis, treatment and care on 10 April 2025**, covering community-acquired acute meningitis across ages >1 month and including diagnostics, antibiotics, adjunctive therapy, supportive care, and long-term effects.[1] On **26 May 2026**, WHO released a practical manual with job aids and decision algorithms to operationalize these recommendations.[2] **STANDARD OF CARE implications:** rapid recognition, prompt effective antibiotics, rational LP/imaging, supportive care, and active management of sequelae. ### NICE NG240 (2024) Important UK practice points include:[3] - Antibiotics within 1 hour of hospital arrival - Ceftriaxone as core empiric therapy; add amoxicillin for Listeria risk - No routine CT before LP - Explicit criteria for imaging-first cases - Dexamethasone for strongly suspected/confirmed bacterial meningitis >3 months, with/before antibiotics if possible - Pathogen-specific durations including 5 days for meningococcus and 10 days for pneumococcus if recovered - No routine fluid restriction - No routine osmotic therapy ### Jurisdiction differences The major difference clinicians encounter is empiric pneumococcal resistance coverage: **many U.S. protocols add vancomycin**, whereas NICE does not use routine vancomycin in its baseline community-acquired regimen. This reflects antimicrobial-resistance assumptions and local epidemiology, not a fundamental disagreement that therapy should be broad enough to cover likely resistant pathogens. --- ## Evidence classification ### STANDARD OF CARE - Immediate IV antibiotics once bacterial meningitis is suspected - LP as early as safely possible - Selective, not routine, neuroimaging before LP - Dexamethasone given before/with first antibiotic dose in appropriate patients - Pathogen-directed narrowing - Public-health intervention for meningococcal disease - Hearing/neurologic follow-up ### EMERGING EVIDENCE - Faster multiplex molecular diagnostics and metagenomic testing - Biomarker-assisted bacterial-vs-viral differentiation - Improved neurocritical-care phenotyping and individualized ICP management - Better long-term neurocognitive rehabilitation strategies ### EXPERIMENTAL / INVESTIGATIONAL Novel host-directed anti-inflammatory strategies, precision diagnostics, and new adjunctive therapies should not replace immediate antibiotics, dexamethasone when indicated, and basic neurocritical/sepsis care outside trials. --- ## Exam-focused review ### Step 1 / Foundations Know: - Bacterial entry into CSF and inflammatory BBB injury - Neutrophilic CSF response - Low CSF glucose from bacterial/leukocyte metabolism and impaired transport - Raised protein from BBB disruption - Encapsulated organisms and splenic/complement defense ### Step 2 CK Classic next-best-step questions: - Suspected meningitis, stable, no focal deficit/ICP sign → **LP promptly**, then immediate antibiotics; do not order routine CT. - Focal deficit or GCS ≤9 → **blood cultures + antibiotics first**, image, then LP when safe. - Older/immunocompromised adult → add **Listeria coverage**. - Meningococcal rash/sepsis → antibiotics immediately + droplet precautions + public health. ### Step 3 / Resident Add: - Empiric regimen selection by age/immunity/resistance - Dexamethasone timing - Interpretation of partially treated CSF - Sepsis/ICP/seizure management - Contact prophylaxis - De-escalation and duration ### MRCP / ABIM / boards Expect nuance on: - CT-before-LP criteria - Pneumococcal vs meningococcal durations - Dexamethasone continuation by organism - Listeria risk - CSF patterns and exceptions - Public-health management --- ## Original MCQs #### 1. A 23-year-old has fever, headache, photophobia and neck stiffness. GCS 15, no focal deficits, normal pupils, stable vital signs. Best next step? A. CT head before any other test B. Lumbar puncture promptly if immediately available and safe, without delaying antibiotics C. MRI brain D. Discharge with oral antibiotics **Answer: B.** Routine neuroimaging before LP is not recommended. LP should precede antibiotics only when safe and when it will not cause clinically significant delay. #### 2. A 67-year-old with suspected meningitis has a new right arm weakness and GCS 8. Best sequence? A. LP first, then antibiotics B. CT first, then blood cultures, then antibiotics C. Blood cultures + immediate antibiotics/dexamethasone as indicated + stabilization, then imaging, then LP when safe D. EEG only **Answer: C.** Focal deficit/GCS ≤9 are imaging-before-LP criteria, but antibiotics must not wait for the scan. #### 3. Which additional empiric coverage is especially important in an older or cell-mediated immunocompromised adult? A. Metronidazole for *C. difficile* B. Ampicillin/amoxicillin for *Listeria monocytogenes* C. Oseltamivir D. Doxycycline for Lyme disease in every case **Answer: B.** Listeria is not reliably covered by third-generation cephalosporins. #### 4. When should dexamethasone ideally be administered? A. Only after culture confirms pneumococcus B. 24 hours after antibiotics C. Before or with the first antibiotic dose D. Only at discharge **Answer: C.** Benefit is linked to blunting the inflammatory response triggered by bacterial lysis. #### 5. CSF shows 2,400 WBC/µL (90% neutrophils), high protein, low glucose, and a low CSF:serum glucose ratio. Most likely diagnosis? A. Typical bacterial meningitis B. Migraine C. Normal CSF D. Isolated peripheral neuropathy **Answer: A.** This is the classic bacterial pattern, although real cases can vary. --- ## References 1. World Health Organization. **WHO guidelines on meningitis diagnosis, treatment and care.** 10 April 2025. ISBN **978-92-4-010804-2**. https://www.who.int/publications/i/item/9789240108042 2. World Health Organization. **WHO practical manual on meningitis diagnosis, treatment and care.** 26 May 2026. ISBN **978-92-4-012102-7**. https://www.who.int/publications/i/item/9789240121027 3. National Institute for Health and Care Excellence (NICE). **Meningitis (bacterial) and meningococcal disease: recognition, diagnosis and management. NG240.** Published March 2024. https://www.nice.org.uk/guidance/ng240 4. NICE. **Rationale and impact: neuroimaging and lumbar puncture, NG240.** 2024. https://www.nice.org.uk/guidance/ng240/chapter/rationale-and-impact 5. de Gans J, van de Beek D; European Dexamethasone in Adulthood Bacterial Meningitis Study Investigators. **Dexamethasone in adults with bacterial meningitis.** *N Engl J Med.* 2002;347:1549–1556. doi: **10.1056/NEJMoa021334**. 6. Centers for Disease Control and Prevention. **Clinical Guidance for Meningococcal Disease.** Updated 2026. https://www.cdc.gov/meningococcal/hcp/clinical-guidance/index.html 7. Médecins Sans Frontières. **Bacterial meningitis — Medical Guidelines.** Current online edition. https://medicalguidelines.msf.org/en/viewport/CG/english/bacterial-meningitis-16689907.html 8. World Health Organization. **Defeating meningitis by 2030: a global road map.** Geneva: WHO; 2021. https://www.who.int/initiatives/defeating-meningitis-by-2030 --- **Review trigger:** Re-review when WHO, NICE, CDC, IDSA/ESCMID, or national antimicrobial guidance changes empiric regimens, dexamethasone recommendations, LP/imaging criteria, meningococcal prophylaxis, or vaccine schedules.1d:T8da2,## One-minute summary The **ABCDE approach** is a structured method for the immediate assessment and treatment of a deteriorating or critically ill patient: **A**irway, **B**reathing, **C**irculation, **D**isability, **E**xposure. The central rule is **treat life-threatening abnormalities as soon as they are found, then reassess from A**.[1,2] ABCDE is designed for **physiologic stabilization before diagnostic completeness**. It is useful in emergency departments, wards, critical care, perioperative settings, clinics, and prehospital care. The 2025 Resuscitation Council UK (RCUK) First Aid Guidelines explicitly endorse a structured ABCDE assessment for people who appear ill, injured, or in shock.[2] **Do not continue a routine ABCDE survey in a patient who is unresponsive and not breathing normally:** activate the cardiac-arrest pathway and start CPR according to current resuscitation guidance.[1,3] ### Core sequence ```text Safety → responsiveness → call for help ↓ A Airway: patent and protected? ↓ B Breathing: oxygenation and ventilation adequate? ↓ C Circulation: perfusion adequate? bleeding? shock? ↓ D Disability: consciousness, pupils, glucose, focal deficit? ↓ E Exposure: hidden clues, temperature, environment? ↓ REASSESS A → B → C → D → E after every important intervention ``` ★ **HIGH YIELD:** ABCDE is a **treat-as-you-find** framework, not “finish the examination, then begin treatment.” --- ## General principles 1. **Treat the greatest immediate threat first.** 2. **Call for help early** if the patient is critically ill or deterioration is likely.[1] 3. **Use the team in parallel:** monitoring, IV access, blood sampling, medication preparation, airway equipment, documentation, and escalation can occur simultaneously.[1] 4. **Reassess after interventions** because the response to treatment determines the next step.[1] 5. **Do not delay lifesaving treatment for a definitive diagnosis.** 6. **Trend physiology**, not isolated numbers: respiratory rate, work of breathing, SpO₂, pulse, blood pressure, mental status, perfusion, urine output, lactate, and response to therapy. 7. **Escalate early** when the patient may require airway expertise, critical care, surgery, interventional radiology, cardiology, neurology, obstetrics, pediatrics, toxicology, or transfer. The ABCDE concept is broadly applicable because airway obstruction, respiratory failure, shock, and neurologic compromise can kill more quickly than many definitive diagnoses can be established.[4] --- ## Clinical applications Use ABCDE for any patient who is **potentially unstable**, including: - sudden deterioration on a ward - severe dyspnea or hypoxemia - shock or suspected sepsis - major bleeding - altered mental status - anaphylaxis - poisoning/overdose - major trauma - peri-arrest states - acute neurologic deterioration - postoperative deterioration - obstetric or pediatric emergencies, with population-specific modifications ### When ABCDE is not the primary pathway If the patient is **unresponsive and not breathing normally**, manage as possible cardiac arrest rather than spending time completing a conventional ABCDE survey.[1,3] ⚠ **COMMON TRAP:** Agonal gasps are abnormal breathing and may occur during cardiac arrest. --- ## First 30 seconds — before A A rapid global impression can reveal critical illness before detailed examination. | Step | What to do | Why it matters | |---|---|---| | Safety | Confirm scene/personal safety; use appropriate PPE | Protects patient and team | | Responsiveness | Speak to the patient; assess response | A coherent answer suggests current airway patency, ventilation, cerebral perfusion, and neurologic function | | Help | Call emergency/resuscitation/senior help early | Complex stabilization is a team task | | Monitoring | Apply pulse oximetry, ECG monitoring, and noninvasive BP early when feasible | Establishes trends and detects deterioration | | Access | Obtain IV access and blood samples when indicated | Enables treatment and diagnostics | | Arrest check | If unresponsive and not breathing normally, activate cardiac-arrest response | CPR/defibrillation take priority | RCUK emphasizes early monitoring, IV access, teamwork, structured communication, and repeated reassessment in critically ill patients.[1] --- ## A — Airway ### Goal Determine whether the airway is **patent, maintainable, and protectable**, and correct life-threatening obstruction immediately. ### Why airway comes first Complete airway obstruction rapidly prevents oxygen delivery. Even partial obstruction can worsen suddenly because of edema, blood, vomitus, secretions, foreign material, trauma, reduced consciousness, or progressive upper-airway pathology.[1,4] ### Airway assessment and immediate management | Component | Assessment | Concerning findings | Immediate action | Anticipate deterioration when… | |---|---|---|---|---| | Speech | Ask patient to speak | Hoarse voice, weak voice, inability to speak | Call for help; prepare airway support | voice is changing, swelling progressing | | Sounds | Listen without a stethoscope first | Stridor, snoring, gurgling, silence | Airway maneuvers, suction, adjuncts, expert help | stridor, swelling, reduced consciousness | | Mouth/oropharynx | Inspect if safe | Blood, vomit, secretions, foreign body, edema | Suction/remove visible obstruction as appropriate | bleeding or secretions continue | | Consciousness | AVPU/GCS trend | Reduced airway protection | Position, adjunct, ventilation; consider definitive airway | GCS/alertness falling | | Neck/face | Trauma, swelling, burns, hematoma | Distortion, rapidly progressive edema | Early anesthetic/ENT/critical-care involvement | expanding neck hematoma, angioedema, inhalation injury | | Air movement | Look/listen/feel | Minimal or absent airflow | Immediate airway opening + ventilation support | fatigue or obstruction worsening | ### Immediate airway interventions Depending on cause, setting, and expertise: - call for expert airway help early - open the airway with appropriate maneuvers - suction blood, vomit, or secretions - remove visible foreign material when appropriate - insert an oropharyngeal or nasopharyngeal airway when indicated - provide bag-mask ventilation if ventilation is inadequate - use a supraglottic airway as a rescue/bridge when appropriate - proceed to tracheal intubation when a definitive airway is required and expertise is available - prepare for emergency front-of-neck access if oxygenation/ventilation cannot be achieved by conventional means RCUK notes that simple airway-opening measures and adjuncts are sufficient in many cases, while tracheal intubation may be required when these fail.[1] #### Causes of threatened airway - reduced consciousness - foreign-body obstruction - blood/vomit/secretions - anaphylaxis/angioedema - inhalational or facial burns - neck hematoma or penetrating injury - upper-airway infection or mass - facial/maxillofacial trauma - seizures - intoxication/sedation #### Trauma note If cervical-spine injury is possible, minimize unnecessary neck movement, but **do not allow spinal precautions to prevent airway opening or oxygenation**. ⚠ **RED FLAGS** - stridor - rapidly progressive facial/tongue/neck swelling - inability to handle secretions - falling level of consciousness - silent airway with respiratory effort - severe facial/neck trauma - smoke inhalation with evolving airway edema ★ **EXAM PEARL:** A patient who can speak normally has a patent airway **at that moment**; it does not guarantee continued patency. --- ## B — Breathing ### Goal Determine whether oxygenation and ventilation are adequate, recognize immediately life-threatening thoracic/respiratory disorders, and support breathing while treating the cause. ### Breathing assessment | Component | Assess | Key abnormal patterns | Immediate implications | |---|---|---|---| | General appearance | agitation, confusion, fatigue, cyanosis | agitation may be early hypoxemia; somnolence may signal hypercapnia/fatigue | escalate monitoring and support | | Respiratory rate | rate and trend | tachypnea, bradypnea, apnea | severe abnormalities can precede arrest | | Speech | full sentences vs words only | short phrases suggest marked respiratory distress | urgent support/treatment | | Work of breathing | accessory muscles, recession, paradoxical movement | increased effort or exhaustion | impending respiratory failure | | Chest movement | symmetry and depth | unilateral reduction | pneumothorax, hemothorax, effusion, obstruction | | Auscultation | bilateral air entry, wheeze, crackles | silent chest, unilateral absent sounds, diffuse wheeze, crackles | targeted emergency therapy | | Percussion | hyperresonance/dullness when useful | hyperresonance vs dullness | pneumothorax vs fluid/consolidation | | SpO₂ | saturation and trend | hypoxemia | oxygen and cause-specific therapy | | CO₂ assessment | capnography/blood gas when indicated | hypercapnia or hypocapnia | assesses ventilation and severity | ### Immediately dangerous breathing problems Think especially about: - tension pneumothorax - severe asthma/bronchospasm - pulmonary edema - massive hemothorax - severe pneumonia - pulmonary embolism - respiratory muscle failure - opioid/sedative respiratory depression - airway obstruction causing secondary ventilatory failure #### Oxygen RCUK’s ABCDE guidance recommends high-concentration oxygen initially for critically ill patients, followed by titration once reliable monitoring is available. For acute respiratory failure, typical targets are **94–98% for most patients** and **88–92% for patients at risk of hypercapnic respiratory failure**, unless an individualized target is documented.[1] #### Ventilatory support If spontaneous ventilation is inadequate: 1. open/secure the airway 2. assist ventilation, commonly beginning with bag-mask ventilation 3. add airway adjuncts when needed 4. escalate to noninvasive or invasive ventilation when appropriate 5. treat the underlying reversible cause #### Bedside tests and monitoring Depending on severity: - continuous pulse oximetry - respiratory-rate monitoring - arterial or venous blood gas - capnography/capnometry - portable chest radiography - lung/pleural point-of-care ultrasound ⚠ **COMMON TRAP:** A normal SpO₂ does **not** prove adequate ventilation. A patient can retain dangerous amounts of CO₂ while oxygen saturation appears acceptable, especially while receiving supplemental oxygen. ✓ **NEXT BEST STEP:** In obvious severe respiratory failure, support oxygenation/ventilation **before** sending the patient for nonessential imaging. --- ## C — Circulation ### Goal Recognize shock, hemorrhage, dysrhythmia, or other circulatory failure and restore adequate tissue perfusion while treating the cause. ### Circulation assessment | Component | What to assess | Concerning findings | What they suggest | |---|---|---|---| | Mental status | confusion, agitation, drowsiness | deterioration | cerebral hypoperfusion, hypoxemia, metabolic cause | | Skin | color, temperature, mottling, diaphoresis | cool/mottled or markedly flushed | shock pattern varies by etiology | | Pulse | rate, rhythm, volume, symmetry | tachycardia, bradycardia, weak pulse, asymmetry | shock, dysrhythmia, vascular emergency | | BP | repeated/trended measurements | hypotension or severe hypertension | shock or hypertensive emergency | | Capillary refill | trend in context | prolonged refill | possible poor peripheral perfusion | | JVP/volume clues | neck veins, edema, mucosa | low vs high filling signs | helps distinguish hypovolemia from obstructive/cardiogenic states | | Bleeding survey | external, GI, thoracic, abdominal, pelvic, retroperitoneal | ongoing blood loss | hemorrhagic shock | | Urine output | trend when catheterization indicated | oliguria | possible renal hypoperfusion | ★ **HIGH YIELD:** **Normal blood pressure does not exclude shock.** Compensatory vasoconstriction may preserve blood pressure despite inadequate tissue perfusion.[1] ### Initial circulatory actions - control obvious external hemorrhage immediately - establish IV access; use IO access when necessary and appropriate - obtain blood samples while access is established - apply continuous cardiac monitoring when indicated - obtain a 12-lead ECG for suspected ischemia/dysrhythmia - use blood gas/lactate and other tests according to context - consider point-of-care ultrasound to help identify shock physiology - begin cause-specific resuscitation without waiting for diagnostic perfection ### Shock framework | Shock type | Typical clues | Immediate priorities | |---|---|---| | Hypovolemic/hemorrhagic | bleeding, low filling signs, tachycardia, cool skin | hemorrhage control, blood products when indicated, cautious crystalloid where appropriate | | Distributive | sepsis/anaphylaxis; may have warm peripheries early | cause-specific treatment, fluids when appropriate, vasopressors when indicated | | Cardiogenic | pulmonary edema, ischemia, high JVP, cool peripheries | cautious fluids, reperfusion/arrhythmia management, vasoactive support, specialist care | | Obstructive | tamponade, tension pneumothorax, massive PE | immediate relief/treatment of obstruction | #### Fluids are not one-size-fits-all Use the suspected cause, comorbidities, dynamic response, and disease-specific guidance to determine fluid strategy. Reassess after each intervention. Excess fluid can worsen cardiogenic shock, pulmonary edema, and some other states. #### Major hemorrhage Priorities may include: - hemorrhage control - major hemorrhage/massive transfusion protocol activation - balanced blood-component or whole-blood strategies according to local protocol - correction of coagulopathy and hypothermia - urgent surgery/interventional radiology - anticoagulant reversal when indicated #### Obstructive emergencies - **tension pneumothorax:** emergency decompression followed by definitive pleural drainage according to trauma/emergency protocol - **cardiac tamponade:** urgent drainage in the appropriate clinical context - **high-risk pulmonary embolism with hemodynamic collapse:** reperfusion strategy according to PE guidance #### Distributive emergencies - **anaphylaxis:** intramuscular epinephrine/adrenaline is first-line - **sepsis/septic shock:** rapid antimicrobials, source control, hemodynamic support according to current sepsis guidance - **adrenal crisis:** glucocorticoid replacement and supportive therapy ### Useful rapid investigations - ECG - CBC - electrolytes/renal function - glucose - blood gas and lactate - coagulation tests - type and screen/crossmatch - troponin when ACS suspected - cultures when infection suspected and they do not delay treatment - POCUS when expertise is available ⚠ **COMMON TRAP:** Treating “hypotension” with repeated fluid boluses without considering cardiogenic or obstructive shock. --- ## D — Disability ### Goal Rapidly assess neurologic function and correct immediately reversible causes of impaired consciousness. ### Disability assessment | Component | What to check | Why | |---|---|---| | Level of consciousness | AVPU/ACVPU and/or GCS | detects deterioration and airway-protection risk | | Pupils | size, symmetry, reactivity | clues to structural neurologic disease or toxins | | Glucose | bedside capillary/POC glucose | hypoglycemia is rapidly reversible | | Focal deficits | face, speech, limbs, gaze as appropriate | stroke/intracranial pathology | | Seizure activity | ongoing or recent | requires urgent treatment and airway consideration | | Toxidrome clues | pupils, skin, secretions, respiratory pattern | directs antidote/supportive therapy | #### First principle: revisit ABC causes Before attributing altered consciousness to a primary brain disorder, reconsider: - hypoxemia - hypercapnia - shock/cerebral hypoperfusion - hypoglycemia - sedatives/opioids/toxins Then consider stroke, intracranial hemorrhage, seizures, meningitis/encephalitis, traumatic brain injury, raised intracranial pressure, electrolyte disorders, and other causes. #### Immediate reversible conditions - hypoglycemia → glucose according to local protocol - opioid toxicity with respiratory depression → airway/ventilation support and naloxone when indicated - ongoing convulsive status epilepticus → benzodiazepine-based emergency seizure treatment followed by protocolized escalation - suspected bacterial meningitis → prompt empiric antimicrobial therapy once appropriate initial steps are taken; do not allow nonessential imaging to create dangerous delay - suspected raised ICP/herniation → urgent neurocritical/neurosurgical pathway and neuroprotective measures ⚠ **COMMON TRAP:** Sending an unstable obtunded patient straight to CT before correcting hypoxia, hypotension, hypoglycemia, or active seizures. #### Airway and consciousness Reduced consciousness may compromise airway protection, but **a single GCS threshold should not be used mechanically without clinical context**. Consider trajectory, airway reflexes, ventilation, oxygenation, aspiration risk, anticipated course, and available expertise. --- ## E — Exposure / Environment ### Goal Perform a sufficiently complete examination to identify hidden pathology while preserving dignity and preventing environmental harm. ### Exposure assessment Look for: - trauma, burns, wounds, bruising - rashes, petechiae, purpura - cellulitis, gangrene, infected surgical sites - bleeding or occult sources of blood loss - edema - abdominal distention or peritonism - limb ischemia - track marks, transdermal patches, toxic exposures - devices, drains, catheters, stomas - bites/stings or retained foreign material - pregnancy-related clues when relevant Measure temperature and manage hypothermia or hyperthermia appropriately. #### Environmental control - replace wet or contaminated clothing - remove ongoing allergen/toxin exposure where safe - begin rewarming or cooling as indicated - re-cover the patient after examination - preserve privacy and dignity ★ **HIGH YIELD:** Exposure means **look thoroughly, then protect the patient from heat loss and environmental harm**. --- ## Reassessment — the essential sixth step ABCDE is **cyclical**, not linear. After every meaningful intervention, ask: - **A:** Is the airway now patent and likely to remain so? - **B:** Has oxygenation, ventilation, respiratory rate, or work of breathing improved? - **C:** Has perfusion improved? What happened to pulse, BP, capillary refill, mental status, urine output, lactate? - **D:** Has consciousness or glucose improved? Any new focal deficit? - **E:** Has a hidden cause or environmental problem been identified? RCUK specifically emphasizes reassessing the patient and evaluating the effect of treatment.[1] ⚠ **RED FLAG:** Any deterioration during later assessment or secondary survey should trigger an immediate return to **A**. --- ## Anticipation of deterioration A high-quality ABCDE assessment does not only ask “what is wrong now?” It asks **“what may fail next?”** | Domain | High-risk features | Prepare for | |---|---|---| | Airway | angioedema, inhalation injury, expanding neck hematoma, worsening consciousness | advanced airway equipment, expert airway team, rescue airway plan | | Breathing | escalating O₂ need, exhaustion, silent chest, rising CO₂ | assisted ventilation, NIV/intubation, critical care | | Circulation | ongoing bleeding, rising lactate, worsening perfusion, escalating vasopressor need | major hemorrhage response, invasive monitoring, definitive source control | | Disability | declining GCS, recurrent seizures, focal deterioration, signs of herniation | airway protection, urgent imaging when stable enough, neurocritical/neurosurgical care | | Exposure | hypothermia, toxin contamination, spreading infection, concealed hemorrhage | rewarming/decontamination/source control | ★ **BOARD-LEVEL POINT:** Deterioration often becomes obvious first as a **trend**—rising respiratory rate, increasing oxygen requirement, narrowing pulse pressure, altered mentation, or increasing support needs—before a single dramatic threshold is crossed. --- ## Crisis resource management and team performance The ABCDE method works best when the team functions deliberately. ### Key principles - establish a clear team leader - allocate tasks explicitly - use **closed-loop communication** - announce important findings and changes - avoid fixation on a single diagnosis - anticipate next steps and prepare equipment early - call additional expertise before crisis becomes irreversible - use structured handover, such as **SBAR** #### Closed-loop communication A task is assigned to a named person, repeated back, completed, and completion is announced. This reduces ambiguity during emergencies. #### Cognitive forcing question At intervals, the team leader should ask: > “What is the immediate threat now, what have we treated, and what could deteriorate next?” --- ## Adjuncts to the ABCDE assessment Adjuncts depend on presentation and should **support rather than delay stabilization**. ### Monitoring - continuous ECG monitoring - pulse oximetry - frequent or continuous blood pressure measurement - capnography where indicated - temperature - urine output in selected critically ill patients ### Access - peripheral IV access - IO access if vascular access is urgently needed and IV access cannot be established promptly - arterial/central access when clinically indicated after initial stabilization ### Point-of-care and laboratory testing Possible tests include: - bedside glucose - ABG/VBG - lactate - CBC - electrolytes and renal function - liver chemistry - coagulation studies - troponin - pregnancy testing when relevant - type and screen/crossmatch - cultures and microbiology when infection is suspected - targeted toxicology testing rather than indiscriminate screening ### Imaging For unstable patients, prioritize tests that can be performed **at the bedside or without delaying treatment**, including: - point-of-care ultrasound - portable chest radiograph - focused trauma ultrasound where appropriate CT and other advanced imaging generally follow once the patient can be transported safely, unless an immediately necessary diagnostic pathway requires otherwise. --- ## Secondary survey and definitive phase Once immediate life threats are controlled: 1. obtain a fuller history 2. perform a head-to-toe examination appropriate to the presentation 3. review medications, allergies, comorbidities, events, and collateral history 4. complete diagnostic testing 5. establish a working diagnosis and differential 6. arrange definitive therapy 7. determine level of care: ward, high-dependency/step-down, ICU, operating room, catheterization lab, stroke unit, transfer, etc. 8. perform structured handover #### SAMPLE history when useful - **S**igns/symptoms - **A**llergies - **M**edications - **P**ast medical history/pregnancy - **L**ast oral intake - **E**vents leading to illness/injury If the patient deteriorates during the secondary survey, **stop and repeat ABCDE immediately**. --- ## Acute management checklist ### Airway - assess ability to speak and airway sounds - inspect for obstruction, blood, vomit, edema, trauma - suction/open airway as needed - use adjuncts when appropriate - call for difficult-airway expertise early - prepare definitive/rescue airway if deterioration is likely ### Breathing - respiratory rate, SpO₂, work of breathing - chest symmetry and bilateral air entry - oxygen to an appropriate target - assist ventilation if inadequate - treat tension pneumothorax, severe bronchospasm, pulmonary edema, or other immediate cause - use blood gas/capnography/POCUS when indicated ### Circulation - pulse, BP, perfusion, capillary refill - search for bleeding - obtain IV/IO access - ECG and blood sampling - cause-specific shock management - reassess after fluids/blood/vasoactive therapy ### Disability - AVPU/ACVPU or GCS - pupils - bedside glucose - focal neurologic signs - seizure/toxin assessment - correct reversible causes promptly ### Exposure - whole-body inspection as appropriate - temperature - remove wet/contaminated clothing or ongoing triggers - prevent heat loss ### Then - reassess A–E - obtain fuller history and examination - pursue definitive diagnosis and treatment - arrange disposition and handover --- ## Diagnostic and management algorithm ```text Acutely unwell / deteriorating patient ↓ Safety + responsiveness + summon help ↓ Unresponsive AND not breathing normally? ├── YES → Cardiac-arrest pathway / CPR / AED-defibrillation as indicated └── NO ↓ A — Airway patent and maintainable? ├── NO → Airway opening/suction/adjunct/ventilation/expert airway help │ ↓ reassess A └── YES ↓ B — Oxygenation and ventilation adequate? ├── NO → Oxygen/ventilatory support + treat immediate respiratory cause │ ↓ reassess A-B └── YES ↓ C — Perfusion adequate? bleeding/shock/arrhythmia? ├── NO → Hemorrhage control + access + cause-specific resuscitation │ ↓ reassess A-C └── YES ↓ D — Neurologic impairment / hypoglycemia / seizure / toxin? ├── YES → Correct reversible cause + urgent neurologic/toxicologic pathway └── NO ↓ E — Expose, inspect, temperature/environment control ↓ REPEAT ABCDE ↓ Secondary survey + diagnostics + definitive care + disposition ``` --- ## Common pitfalls | Pitfall | Why dangerous | Better practice | |---|---|---| | Long history before stabilization | delays treatment of immediate threats | ABCDE first, fuller history later | | Completing all of A–E before treating | allows reversible deterioration to progress | treat abnormalities as found | | Focusing on diagnosis rather than physiology | may delay oxygenation/perfusion support | stabilize first, diagnose in parallel | | Normal BP = no shock | compensated shock may preserve BP | assess global perfusion and trends | | Normal SpO₂ = adequate ventilation | hypercapnia may be missed | assess respiratory effort and CO₂ when indicated | | Repeated fluid boluses for every hypotensive patient | may worsen cardiogenic/obstructive states | use cause-specific resuscitation | | Missing bedside glucose | overlooks a reversible cause of altered consciousness | check early in D | | Failure to expose | hidden rash, bleeding, trauma, devices, infection missed | perform adequate whole-body inspection | | Failure to re-cover | promotes hypothermia and loss of dignity | exposure + environmental control | | No reassessment | treatment may fail or patient may deteriorate | repeat ABCDE after interventions | | Poor task allocation | delays parallel care | leadership + closed-loop communication | --- ## Special populations ### Trauma Trauma systems may use **ABCDE** or **XABCDE**, placing catastrophic external hemorrhage control before airway when exsanguinating bleeding is immediately apparent. Follow the trauma protocol in use locally. Cervical-spine precautions modify airway technique but must not prevent oxygenation or ventilation. ### Pediatrics The same physiologic priorities apply, but airway anatomy, normal vital-sign ranges, fluid therapy, drug dosing, shock patterns, and deterioration differ substantially by age. Use current pediatric life-support guidance. ### Pregnancy Apply ABCDE with pregnancy physiology in mind. Maternal oxygenation and perfusion are the primary determinants of fetal oxygen delivery. Advanced pregnancy may require positioning strategies to reduce aortocaval compression during resuscitative care. ### Older adults Older patients may have limited physiologic reserve, atypical presentations, beta-blocker use that blunts tachycardia, renal vulnerability, and high risk from both under- and over-resuscitation. ### Toxicology Airway, ventilation, ECG, glucose, temperature, and toxidrome recognition are especially important. Use targeted antidotes when indicated, but supportive ABC care remains fundamental. --- ## Evidence and current guidance ### ESTABLISHED STANDARD OF CARE - Structured ABCDE assessment for acutely unwell patients is longstanding and internationally used.[1,4] - Treat life-threatening abnormalities as they are identified and reassess frequently.[1] - If the patient is unresponsive and not breathing normally, switch immediately to cardiac-arrest management.[1,3] - Early teamwork, monitoring, vascular access, and structured communication improve the efficiency of emergency assessment.[1] ### NEW / UPDATED GUIDANCE The **2025 RCUK First Aid Guidelines** introduced first aid as a dedicated guideline chapter and explicitly recommend structured ABCDE assessment for a person who appears ill, injured, or in shock.[2] The **2025 AHA Adult Basic Life Support Guidelines** supersede the prior full 2020 BLS set and update adult cardiac-arrest, respiratory-arrest, and foreign-body-airway-obstruction guidance.[3] ### EMERGING EVIDENCE ABCDE itself is primarily a structured clinical framework rather than a single therapeutic intervention. Evidence evaluating its effect on outcomes is less extensive than evidence for individual treatments embedded within the framework. Its enduring value is in prioritization, communication, repeated reassessment, and early correction of physiologic threats.[4] --- ## Exam-focused review ### USMLE Step 1 — mechanisms Know the physiology behind: - airway obstruction → alveolar hypoventilation/hypoxemia - respiratory failure → hypoxemia and/or hypercapnia - shock → reduced tissue perfusion → anaerobic metabolism/lactate - sympathetic compensation → tachycardia and vasoconstriction - hypoglycemia → neuroglycopenia ### USMLE Step 2 CK — next best step Common pattern: > **Unstable patient + possible diagnosis → stabilize first.** Examples: - airway compromise before CT - severe respiratory failure before definitive imaging - active major hemorrhage before prolonged diagnostic workup - hypoglycemia correction before broad neurologic testing ### Step 3 / Resident Expect decisions about: - when to escalate to airway/critical care - shock subtype and resuscitation strategy - reassessment after interventions - disposition and transfer - complications of treatment ### MRCP / ABIM / Board level High-yield nuances: - normal BP does not exclude shock - oxygenation and ventilation are distinct - a single GCS number does not automatically determine airway management - fluid strategy depends on shock phenotype and comorbidity - trends and response to treatment often matter more than single measurements - cognitive errors such as fixation and premature closure are important in deteriorating patients --- ## Original MCQs ### Question 1 — next best step A 67-year-old patient becomes drowsy and tachypneic on the ward. SpO₂ is 82% on room air, BP is 118/70 mmHg, and the patient can answer only one-word questions. What is the best immediate approach? A. Obtain CT pulmonary angiography B. Complete a full neurologic examination C. Begin ABCDE stabilization with immediate respiratory support D. Wait for arterial blood gas results before treatment E. Obtain a detailed medication history **Answer: C.** **Explanation:** The patient is unstable with severe hypoxemia and respiratory distress. Stabilization of airway/breathing takes priority over definitive diagnosis. Imaging and detailed history follow once immediate physiologic threats are addressed.[1] **Tested concept:** next-best-step prioritization **Difficulty:** Step 2 CK / MRCP --- ### Question 2 — shock A trauma patient is tachycardic, cool, clammy, and confused. BP is 112/74 mmHg. Which statement is most accurate? A. Shock is excluded because systolic BP is >100 mmHg B. The patient may have compensated shock despite normal BP C. Lactate must be elevated before shock can be diagnosed D. Hypotension is required before hemorrhage control E. CT should precede resuscitation **Answer: B.** **Explanation:** Compensatory vasoconstriction can preserve blood pressure despite reduced perfusion. Clinical perfusion and trends matter.[1] **Tested concept:** compensated shock **Difficulty:** Step 2 CK / Step 3 --- ### Question 3 — ventilation A patient with COPD is somnolent on supplemental oxygen with SpO₂ 95%. Which statement is most important? A. Normal SpO₂ excludes respiratory failure B. Pulse oximetry directly measures PaCO₂ C. Hypercapnia may still be present despite acceptable SpO₂ D. Oxygen should always be stopped immediately E. Respiratory rate is not useful **Answer: C.** **Explanation:** Pulse oximetry assesses oxygen saturation, not ventilation or CO₂ clearance. Blood gas and clinical assessment may reveal hypercapnic respiratory failure. **Tested concept:** oxygenation vs ventilation **Difficulty:** MRCP / ABIM --- ### Question 4 — disability An obtunded patient arrives after an unwitnessed collapse. Which bedside test belongs early in the disability assessment because it identifies a rapidly reversible cause? A. EEG B. Lumbar puncture C. Blood glucose D. MRI brain E. Carotid Doppler **Answer: C.** **Explanation:** Hypoglycemia is a rapidly reversible cause of altered mental status and should be checked promptly during D.[1] **Tested concept:** reversible causes of altered consciousness **Difficulty:** Step 2 CK --- ### Question 5 — reassessment After airway suction and bag-mask ventilation, the patient's oxygen saturation improves. What is the best next action? A. Proceed directly to discharge planning B. Continue to C without checking the airway again C. Reassess from A, then continue through ABCDE D. Wait 30 minutes before reassessment E. Perform only a neurologic examination **Answer: C.** **Explanation:** ABCDE is iterative. After an important intervention, reassess the effect of treatment and return to the beginning of the sequence.[1] **Tested concept:** reassessment **Difficulty:** Foundation / Step 2 CK --- ## Cross-links for the library Future linked articles should include: - Airway management - Oxygen therapy - Respiratory failure - Shock - Sepsis and septic shock - Anaphylaxis - Altered mental status and coma - Trauma primary and secondary survey - Cardiac arrest and CPR - Point-of-care ultrasound in shock --- ## References 1. **Resuscitation Council UK.** *The ABCDE Approach.* Updated July 2024. Official clinical guidance. https://www.resus.org.uk/library/abcde-approach 2. **Resuscitation Council UK.** *First Aid Guidelines — 2025 Resuscitation Guidelines.* Published October 27, 2025. Based on European Resuscitation Council Guidelines 2025 First Aid. https://www.resus.org.uk/professional-library/2025-resuscitation-guidelines/first-aid-guidelines 3. **Kleinman ME, Buick JE, Huber N, et al.** Part 7: Adult Basic Life Support: 2025 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. *Circulation.* 2025;152(Suppl 2):S448-S478. doi:10.1161/CIR.0000000000001369. 4. **Thim T, Krarup NHV, Grove EL, Rohde CV, Løfgren B.** Initial assessment and treatment with the Airway, Breathing, Circulation, Disability, Exposure (ABCDE) approach. *International Journal of General Medicine.* 2012;5:117-121. doi:10.2147/IJGM.S28478. PMID:22319249. --- ### Editorial note This article is an original synthesis for Dr Note Library. It is designed to provide layered learning from foundational physiology through clinical stabilization and board-level reasoning. It should be updated whenever major resuscitation, airway, oxygen, trauma, or critical-care guidance changes.7:["$","$L17",null,{"article":{"id":"medical-0008","title":"Acute Ischemic Stroke","slug":"acute-ischemic-stroke","description":"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…","aliases":[],"category":"Neurology","tags":["Neurology","Vascular Neurology","Emergency Medicine"],"updatedAt":"2026-09-08","body":"$18","headings":[{"id":"one-minute-summary","text":"One-minute summary","level":2},{"id":"1-core-concepts","text":"1. 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