Abstract WP7: Early Neurological Improvement With First Pass Effect is More Common in Early Window Endovascular Intervention for Emergent Large Vessel Occlusion

Abstract

Background: First pass effect (FPE), defined as complete reperfusion within one procedural pass during endovascular therapy, is associated with higher rates of a favorable clinical outcome. We aimed to see if early neurological improvement (ENI) associated with FPE differs between early and late window thrombectomy. Methods: We reviewed consecutive acute ischemic strokes that underwent mechanical thrombectomy at a comprehensive stroke center from January 2016 through December 2018. Two patient groups were established: early ( < 6 hours from onset) and late (> 6 hours from onset) window intervention groups who achieved FPE. Baseline characteristics were collected and the presence of ENI was defined as >40% reduction of NIH Stroke Scale score from pre-procedure to next-day. We compared frequencies of ENI within the two time window groups. Results: Of 285 patients who underwent intervention, 116 had early interventions and 151 had late interventions. The overall frequency of FPE in the two time windows was not different (37.9% early and 30.5% late, p=0.2). However, FPE in the early group was associated with ENI in 33/41 (80.48%) cases compared to 25/44 (56.81%) cases in the late group ( p = 0.019). The early intervention group was 3.14 times as likely as the late group to achieve ENI with first pass recanalization (95% Confidence Interval, 1.18-8.32) Conclusion: First pass effect achieves early neurologic improvement more often in early window endovascular intervention compared to late window interventions.