## Clinical Context This patient presents with acute ischemic stroke at 3 hours post-onset with imaging-confirmed large vessel occlusion (LVO) at the left M1 segment. He is within the 4.5-hour window for IV thrombolysis and has no stated contraindications. Current guidelines recommend IV alteplase followed by mechanical thrombectomy (bridging strategy) for eligible patients. ## Key Imaging Findings | Finding | Significance | |---------|-------------| | DWI hyperintensity + ADC hypointensity | Acute ischemia (cytotoxic edema) — confirms ischemic stroke | | CT angiography M1 occlusion | Large vessel occlusion — thrombectomy candidate | | Non-contrast CT negative | Rules out hemorrhage | | Time window 3 hours | Within IV thrombolysis window (< 4.5 hrs) AND thrombectomy window | ## Management Algorithm **Step 1:** Confirm ischemic stroke, rule out hemorrhage (done — NCCT negative) **Step 2:** Assess IV thrombolysis eligibility — patient is within 4.5 hours, BP manageable, no stated contraindications **Step 3:** Administer IV alteplase 0.9 mg/kg (10% bolus, remainder over 60 min) **Step 4:** Proceed to mechanical thrombectomy — for M1 occlusion, thrombectomy is indicated regardless of thrombolysis response **Key Point:** Per AHA/ASA 2019 guidelines and ESO 2021 guidelines, eligible patients with LVO presenting within 4.5 hours should receive IV alteplase AND mechanical thrombectomy (bridging thrombolysis). Thrombectomy-first (without IV thrombolysis) is reserved for patients with contraindications to alteplase or in centers with direct-to-angio protocols under specific trial conditions (DIRECT-MT, DEVT trials showed non-inferiority in selected populations, but bridging remains standard of care in most guidelines). **High-Yield:** Option A correctly describes the bridging strategy — IV alteplase first, followed by thrombectomy. The "30-minute" qualifier in option A is non-standard (thrombectomy proceeds regardless of thrombolysis response for M1 LVO), but the overall strategy of IV alteplase + thrombectomy is the guideline-recommended approach for this clinical scenario. **Clinical Pearl:** IV thrombolysis alone achieves only ~10% recanalization for proximal M1 occlusions; however, it is still administered first (when eligible) because it may partially lyse clot, improve collateral flow, and does not delay thrombectomy when both are planned concurrently. The combination is superior to either alone in the early window. ## Why Not Option B (Thrombectomy Alone)? - Thrombectomy-first without IV thrombolysis is NOT standard of care for patients eligible for alteplase within 4.5 hours per AHA/ASA guidelines - DIRECT-MT and DEVT trials showed non-inferiority in Chinese populations but have not changed global guidelines to recommend omitting alteplase universally - In the absence of a stated contraindication to alteplase, bridging therapy (Option A) remains the recommended approach ## Why Not Options C or D? - Clopidogrel loading and aspirin are antiplatelet agents — not appropriate as primary intervention for acute LVO stroke requiring reperfusion therapy - Observation for spontaneous recanalization is inappropriate for M1 LVO [cite:Harrison 21e Ch 435; AHA/ASA Guidelines for Early Management of Acute Ischemic Stroke 2019, Stroke 50:e344–e418] 
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