A 58-year-old man with a 10-year history of atrial fibrillation presents to the emergency department with acute onset left-sided weakness and speech difficulty. CT head shows no acute intracranial hemorrhage. His blood pressure is 165/95 mmHg, heart rate 110/min and irregular. He is on aspirin monotherapy. What is the most appropriate immediate next step in management?

Explanation

## Clinical Context This is an acute ischemic stroke in a 58-year-old man with atrial fibrillation (AF). The CT head has excluded hemorrhage. The question asks for the **most appropriate immediate next step**, and the stem implies acute/early presentation ("acute onset") within the thrombolytic window. ## Pathophysiology of Cardioembolic Stroke **Key Point:** Atrial fibrillation causes blood stasis in the left atrial appendage, leading to thrombus formation. These thrombi embolize to the cerebral circulation, causing acute ischemic stroke. AF accounts for ~20% of all ischemic strokes and is the most common cardioembolic source. ## Management Algorithm ```mermaid flowchart TD A[Acute ischemic stroke presentation]:::outcome --> B{CT head: hemorrhage?}:::decision B -->|Yes| C[No thrombolytics / No anticoagulation]:::urgent B -->|No| D{Symptom onset < 4.5 hours? No contraindications?}:::decision D -->|Yes| E[IV Alteplase thrombolysis — FIRST priority]:::action D -->|No / beyond window| F[Anticoagulation for AF-related cardioembolic stroke]:::action E --> G[Followed by anticoagulation after 24 hours]:::action ``` ## Why IV Thrombolysis (Alteplase) is the Correct Immediate Next Step **High-Yield (AHA/ASA 2019 Guidelines):** For eligible patients with acute ischemic stroke presenting within **4.5 hours** of symptom onset, IV alteplase is the **first-line, most time-sensitive intervention** — regardless of the underlying etiology (including AF). The stem describes "acute onset," placing this patient within the thrombolytic window. **Clinical Pearl:** The presence of AF does not exclude thrombolysis. In fact, cardioembolic strokes from AF often respond well to thrombolysis because the clot burden is typically fibrin-rich. Anticoagulation with UFH/LMWH is **not** initiated acutely in the immediate post-stroke period due to risk of hemorrhagic transformation; it is started after 24 hours and post-thrombolysis imaging. **Key Point (Harrison's Principles, 21st ed.):** IV alteplase (0.9 mg/kg, max 90 mg) given within 4.5 hours of ischemic stroke onset significantly improves functional outcomes. Anticoagulation is deferred for at least 24 hours after thrombolysis to minimize hemorrhagic transformation risk. ## Why the Other Options Are Incorrect - **Option B (IV UFH immediately):** Immediate anticoagulation in acute ischemic stroke is NOT recommended as the first step — it increases hemorrhagic transformation risk. UFH/anticoagulation is used for secondary prevention after the acute phase (typically 24–48 hours post-stroke, after repeat imaging). - **Option C (Dual antiplatelet therapy):** Aspirin + clopidogrel dual therapy is used in minor ischemic stroke/TIA (POINT/CHANCE trials), not in acute cardioembolic stroke from AF where anticoagulation is the definitive secondary prevention strategy. - **Option D (Carotid duplex ultrasound):** Carotid imaging is relevant for large-vessel atherosclerotic stroke, not the immediate priority in a patient with confirmed AF as the likely cardioembolic source. ## Next Steps After Acute Phase 1. Repeat CT/MRI at 24 hours post-thrombolysis before initiating anticoagulation 2. Transition to oral anticoagulation (DOAC preferred over warfarin per ESC 2020) for long-term AF stroke prevention 3. Rate/rhythm control of AF 4. Echocardiography (TTE/TEE) to assess left atrial appendage thrombus **Reference:** AHA/ASA Guidelines for Early Management of Acute Ischemic Stroke (2019); Harrison's Principles of Internal Medicine, 21st ed., Chapter on Cerebrovascular Disease.