POSITIVE Stroke Clinical Trial

Intravenous (IV) tissue plasminogen activator (tPA) administration has been shown to be safe and effective for treatment of AIS within 3 hours of symptom onset, and newer evidence has shown potential benefit out to 4.5 hours. Mechanical thrombectomy for AIS patients has been shown in clinical trials to be safe up to 8 hours after symptom onset. The rapid progression of thrombectomy devices over the last several years has resulted in faster recanalization times while maintaining a high degree of safety. This has resulted in improved patient outcomes, similar to prior randomized trial data showing improved outcomes over medical therapy or earlier devices. Data from the MERCI trial suggests that patients \> 85 as well as those with a baseline NIHSS score \> 30 are unlikely to benefit from thrombectomy. Patients with rapidly improving neurologic deficits likely will have an excellent recovery with conventional care, precluding the ability to detect a beneficial treatment effect of thrombectomy. Pilot data incorporating physiologic imaging has shown that appropriate patients can be selected for thrombectomy. This selection methodology has shown the ability to maintain the same level of safety and efficacy as those patients treated in the highly selective environment of a clinical trial, despite presenting far beyond accepted time based standards. Vertebrobasilar occlusion patients are excluded to maintain a homogenous study population, particularly since no data currently is available addressing the comparability of imaging penumbral patterns in the anterior vs. posterior circulation. This has also been shown to be reproducible at multiple centers and with different imaging modalities. However, all prospective interventional stroke studies performed to date have been restricted by the 8-hour time window.