In the recent guidelines on early management of stroke, IV alteplase is recommended for selected patients who may be treated within 3 hours (level of evidence ‒ A) and 3-4.5 hours (level of evidence – B) of ischemic stroke symptom onset or last known well or at baseline state. The guidelines go on to state that IV alteplase should be administered even if endovascular therapy is being considered. The guidelines then go on to give criteria for using endovascular therapy within 6 hours if patients meet the inclusion criteria. In discussing the study above, the guidelines state, “In selected patients with acute ischemic stroke within 6 to 16 hours of last known normal who have large vessel obstruction in the anterior circulation and meet eligibility criteria, mechanical thrombectomy is recommended.”¹ The improvement in functional outcome in this study is probably the result of careful patient selection for patients with significant amounts of remaining ischemic brain tissue that was not yet infarcted. This selection was achieved through strict eligibility criteria that assessed the volume of partially ischemic tissue to infarcted tissue and required a minimum absolute volume of potentially reversible ischemic tissue. Estimates of the volume of the ischemic core and the partially ischemic at-risk regions were derived from CT perfusion or MRI diffusion and perfusion scans. The important take-home for primary care is that for selected patients in centers with the availability of mechanical thrombectomy, patients may derive substantial benefit up to 16 hours after clinical onset of stroke. — Neil Skolnik, MD

1. Powers WJ, Rabinstein AA, Ackerson T, et al; on behalf of the American Heart Association Stroke Council. 2018 Guidelines for the early management of patients with acute ischemic stroke: A guideline for healthcare professionals from the American Heart Association/American Stroke Association. [Published online ahead of print January 24, 2018]. Stroke. doi:10.1161/STR.0000000000000158.