Which statement about the thrombolysis time window is correct?

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

Answer: (D)

In acute ischemic stroke, the chance of saving brain tissue from ischemia depends heavily on how quickly treatment is given. Intravenous thrombolysis with alteplase has a defined time window to maximize benefit and minimize harm. Earlier administration improves outcomes, and the standard approach has evolved from a strict 3-hour limit to including a longer window for select patients. The evidence supporting extending the window comes from trials like ECASS III, which showed that patients treated within 3 to 4.5 hours after onset could have better functional outcomes than those treated later, provided they meet specific eligibility criteria and have no contraindications. This makes 4.5 hours the upper limit for IV thrombolysis in eligible patients. Treatments beyond this window have not consistently shown benefit and carry higher risk, such as intracranial hemorrhage. So the correct statement is that thrombolysis can be given within 4.5 hours of symptom onset, with careful patient selection.