A 67-year-old man presents with acute left-sided weakness 2 hours after onset. CT head is negative for hemorrhage. His BP is 185/100 mmHg. NIHSS score is 14. There is no contraindication to thrombolysis. He is given IV alteplase. Based on the DAWN and DEFUSE-3 trials, if the patient were presenting 8–24 hours after symptom onset with penumbra imaging mismatch, the recommended intervention would be:
- A IV alteplase regardless of time window
- B Dual antiplatelet therapy (aspirin + clopidogrel) for 21 days
- C Endovascular thrombectomy (mechanical) if large vessel occlusion with mismatch ✓
- D Emergent carotid endarterectomy if ipsilateral stenosis >70%
Explanation
The DAWN trial (2018, NEJM) and DEFUSE-3 trial extended the window for endovascular thrombectomy (EVT) to 24 hours and 16 hours post-onset respectively in patients with large vessel occlusion (LVO) and favorable penumbra-core mismatch on perfusion imaging (CT perfusion/DWI-MRI). EVT with stent-retriever devices yielded significantly improved functional outcomes (mRS 0–2) versus standard care. The concept of 'tissue is the clock' — salvageable penumbra, not arbitrary time, determines EVT eligibility. IV alteplase cannot be given beyond 4.5 hours from onset. Dual antiplatelet is for minor stroke/TIA (POINT/CHANCE trials). Carotid endarterectomy is for symptomatic stenosis but not in the acute hyperacute stroke phase.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.