A 68-year-old hypertensive man presents with sudden-onset aphasia and right hemiplegia at 11 AM. The last known well time was 10:30 AM. CT brain shows no haemorrhage or established infarct, and CT perfusion shows a large penumbra. What is the extended time window for IV alteplase administration per current guidelines (AHA/ASA 2019)?
- A 4.5 hours from last known well time for eligible patients ✓
- B 3 hours from symptom onset for all patients
- C 6 hours from symptom onset regardless of penumbra
- D 24 hours from symptom onset if penumbra-guided imaging criteria are met
Correct answer: A. 4.5 hours from last known well time for eligible patients
Explanation
AHA/ASA 2019 guidelines extended the IV alteplase window to 4.5 hours from last known well time for carefully selected patients (excluding those >80 years, severe stroke NIHSS >25, prior stroke with diabetes, anticoagulant use), based on ECASS III and SITS-ISTR data. The WAKE-UP trial (2018) further showed MRI-guided IV alteplase benefit in unknown-onset stroke with diffusion-FLAIR mismatch. For mechanical thrombectomy (large vessel occlusion), the time window extends to 24 hours based on DAWN and DEFUSE-3 trials using perfusion-core mismatch imaging.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.