Advances in intravenous thrombolytic therapy for treatment of acute stroke.

Intravenous tissue plasminogen activator (tPA) is an effective therapy for treatment of acute ischemic stroke when administered within 3 hours of symptom onset. Three large randomized clinical trials that have attempted to extend the time window for tPA treatment beyond 3 hours have failed to demonstrate convincing evidence of efficacy. A recently published prospective, monitored, multicenter study of 389 patients, who were treated with tPA for ischemic stroke at 57 medical centers (24 academic, 33 community) across the United States, demonstrated favorable outcomes and low rates of symptomatic intracerebral hemorrhage. Recent advances in neuroimaging, including diffusion-weighted MRI (DWI) and perfusion-weighted MRI (PWI), have the potential to differentiate salvageable ischemic brain tissue from irreversibly injured tissue. Preliminary data suggest that acute stroke patients who present with a PWI lesion that is considerably larger than the initial DWI lesion may be good candidates for intravenous thrombolysis, even beyond 3 hours after symptom onset. Additional research is required to clarify the optimal use of these diagnostic techniques and their cost-effectiveness.