Time to Treatment in Stroke Thrombectomy and Outcomes in the Extended Time Window

BACKGROUND AND OBJECTIVES: Time to endovascular thrombectomy (EVT) is a critical determinant of outcomes for large vessel occlusion (LVO) strokes presenting within 6 hours of onset. Its impact in the extended (6-24-hour) window remains uncertain. We aimed to evaluate the association between treatment times and outcomes in this window. METHODS: Individual patient-level data from 6 randomized trials enrolling patients in the extended window were pooled. The primary outcome was degree of disability at 90 days (modified Rankin Scale [mRS] 0-6). Secondary outcomes included functional independence (mRS 0-2), mortality, and symptomatic intracranial hemorrhage. RESULTS: = 0.038). DISCUSSION: This study demonstrates that the benefit of EVT is consistently preserved across the extended (6-24-hour) time window when patients are selected using advanced imaging criteria. In this highly selected population, enriched with slow progressors, the apparent increase in treatment effect with longer onset-to-presentation times reflects the validity of physiologic selection rather than true time insensitivity. However, this observation should not diminish the critical importance of time: imaging-based selection effectively resets the treatment clock, masking the harmful impact of prehospital delays. Notably, longer in-hospital delays were strongly associated with worse outcomes, reinforcing that "time is brain," even in extended-window cohorts.