Ma H, et al. - Intravenous thrombolysis for an acute ischemic stroke usually needs to be initiated within 4.5 hours of symptom onset, however, some studies indicate there’re may be more time for patients with ischemic but not yet infarcted brain tissue on the image. Study participants included patients with ischemic stroke who had hypoperfused but salvageable regions of brain found on automated perfusion imaging. Between 4.5 and 9.0 hours after the onset of stroke or on stroke awakening (if within 9 hours from the midpoint of sleep), participants in the study were randomly assigned to receive intravenous alteplase or placebo. According to this multicenter, randomized, placebo-controlled trial, the use of alteplase between 4.5 and 9.0 hours after stroke onset or at the time the patient awoke with stroke symptoms resulted in a higher percentage of patients with no or minor neurologic deficits vs the use of placebo among the patients in this trial who had ischemic stroke and salvageable brain tissue. In the alteplase group, there were more cases of symptomatic cerebral hemorrhage vs the placebo group.