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 brain (non-contrast) is normal. His wife reports he stopped taking warfarin 2 weeks ago due to cost concerns. Vital signs are stable, and it is 90 minutes since symptom onset. What is the most appropriate immediate next step?

Explanation

## Clinical Context This is a case of acute ischemic stroke in the setting of cardioembolic risk (atrial fibrillation off anticoagulation). The patient is within the thrombolytic window (90 minutes from symptom onset). ## Pathophysiology of Cardioembolic Stroke **Key Point:** Atrial fibrillation causes blood stasis in the left atrial appendage, promoting thrombus formation. When anticoagulation is withdrawn, the risk of thromboembolism rises sharply. The thrombus dislodges and travels to cerebral arteries, causing acute ischemia. ## Management Algorithm ```mermaid flowchart TD A[Acute stroke symptoms]:::outcome --> B{Time since onset?}:::decision B -->|< 4.5 hours| C[Non-contrast CT to exclude hemorrhage]:::action C --> D{Hemorrhage present?}:::decision D -->|No| E[CTA head/neck to confirm occlusion]:::action E --> F{Occlusion confirmed?}:::decision F -->|Yes| G[IV thrombolysis + consider thrombectomy]:::action F -->|No| H[Antiplatelet therapy]:::action B -->|> 4.5 hours| I[Supportive care + antiplatelet]:::action ``` ## Why This Step is Correct 1. **Non-contrast CT** has already ruled out hemorrhage (essential before thrombolysis) 2. **CTA head and neck** confirms the presence of arterial occlusion and identifies its location 3. **Thrombolysis** (alteplase IV) is indicated within 4.5 hours of symptom onset in ischemic stroke without contraindications 4. This patient has no contraindications: stable vitals, no recent surgery, no active bleeding **High-Yield:** The CTA is the pivotal diagnostic step that confirms thromboembolism and guides the decision to thrombolyse. It takes only 5–10 minutes and should not delay thrombolysis if the clinical picture is clear. **Clinical Pearl:** In cardioembolic stroke, the embolus typically lodges at arterial bifurcations (middle cerebral artery bifurcation is most common). CTA visualizes this occlusion and helps triage for mechanical thrombectomy if indicated. ## Anticoagulation Post-Thrombolysis After thrombolysis, anticoagulation (heparin, then warfarin or DOAC) is initiated to prevent recurrent thromboembolism, but this is a secondary step—not the immediate next action.