What is the critical time window for thrombolysis in eligible acute ischemic stroke patients?

• A. Within 3 hours of onset
• B. Within 4 hours of onset
• C. Within 5 hours of onset
• D. Within 4.5 hours of onset

Answer: (D)

In acute ischemic stroke, restoring blood flow as quickly as possible improves outcome because brain tissue dies rapidly without perfusion. IV thrombolysis with rtPA can be beneficial not only in the classic 3-hour window but, in carefully selected patients, up to 4.5 hours after onset. This extended window came from trial data showing functional benefits with acceptable bleeding risk when treatment is given within 4.5 hours, with appropriate patient selection and screening for contraindications. Beyond 4.5 hours, the potential benefits diminish and the risks increase, so the standard recommended window for eligible patients is within 4.5 hours of onset.