A 72-year-old woman with atrial fibrillation (not on anticoagulation) presents 6 hours after sudden onset of right-sided hemiparesis and aphasia. Non-contrast CT head is normal. MRI DWI shows acute infarction in the left middle cerebral artery territory. She is ineligible for IV thrombolysis due to recent hip surgery (8 days ago). What is the most appropriate next step in management?

Explanation

## Clinical Context This patient is **outside the 4.5-hour IV thrombolysis window** (6 hours from onset) but may still be eligible for **mechanical thrombectomy (MT)** if a large vessel occlusion (LVO) is present. Recent hip surgery (8 days ago) is a relative contraindication to IV thrombolysis but NOT to mechanical thrombectomy. ## Key Point: **Mechanical thrombectomy is indicated for acute ischemic stroke due to large vessel occlusion within 24 hours of symptom onset (or up to 48 hours with appropriate imaging criteria showing salvageable tissue).** [cite:Harrison 21e Ch 446] ## Thrombectomy Eligibility Window ```mermaid flowchart TD A[Acute ischemic stroke]:::outcome --> B{Time since onset?}:::decision B -->|< 4.5 hours| C[IV thrombolysis eligible?]:::decision B -->|4.5-24 hours| D[Check for LVO on CTA/MRA]:::action D --> E{LVO present?}:::decision E -->|Yes| F[Mechanical thrombectomy]:::action E -->|No| G[Medical management + antiplatelet]:::action C -->|Yes| H[IV rt-PA]:::action C -->|No| D F --> I[Reperfusion & improved outcome]:::outcome G --> J[Secondary prevention]:::outcome ``` ## Why CTA/MRA is the Next Step **High-Yield:** The patient has: - Acute ischemic stroke confirmed on MRI DWI - Presentation 6 hours from onset (within extended MT window) - Relative contraindication to IV thrombolysis (recent surgery) - **No absolute contraindication to mechanical thrombectomy** **Clinical Pearl:** Recent surgery (8 days ago) is a **relative contraindication** to IV thrombolysis because of bleeding risk, but it does NOT preclude mechanical thrombectomy, which is a catheter-based intervention without systemic fibrinolysis. ## Mechanical Thrombectomy Criteria | Criterion | Details | |-----------|----------| | **Time window** | ≤ 24 hours from symptom onset (or ≤ 48 hours with advanced imaging showing salvageable tissue) | | **Vessel involved** | Large vessel occlusion (ICA, MCA M1/M2, basilar artery) | | **NIHSS** | Generally ≥ 6 (moderate to severe deficit) | | **ASPECTS score** | ≥ 6 on CT or MRI (indicates salvageable brain tissue) | | **Contraindications** | Active bleeding, severe coagulopathy; recent intracranial surgery (relative) | **Key Point:** MRI DWI already shows acute infarction, but CTA/MRA is still needed to: 1. Confirm presence and location of large vessel occlusion 2. Assess collateral circulation 3. Determine candidacy for thrombectomy 4. Exclude hemorrhage (already done with non-contrast CT) ## Why Aspirin Alone is Insufficient **Warning:** Starting aspirin and observing (Option A) is **suboptimal** because it does not address a potentially salvageable large vessel occlusion. If an LVO is present, mechanical thrombectomy offers significantly better outcomes than medical management alone. ## Atrial Fibrillation & Anticoagulation This patient has AF without prior anticoagulation — she is at high cardioembolic risk. However: - **Acute phase:** Anticoagulation (heparin, LMWH) is NOT routinely initiated in the first 24 hours unless there is a specific indication (e.g., arterial dissection, cardioembolic source with high recurrence risk). - **After acute phase:** Anticoagulation (warfarin or DOAC) should be started based on CHA₂DS₂-VASc and HAS-BLED scores. **Clinical Pearl:** Heparin in the acute phase does NOT improve outcomes in most ischemic strokes and may increase bleeding risk, especially with recent surgery.