Havenon, Adam H de

Objective: To determine whether first pass effect (FPE) after mechanical thrombectomy (MT) for anterior circulation large vessel occlusion acute ischemic stroke (LVO-AIS) is modified by procedural time (PT). Methods: The Stroke Thrombectomy and Aneurysm Registry (STAR), a multi-center international dataset, was retrospectively analyzed for anterior circulation LVO-AIS treated by MT who achieved excellent reperfusion (TICI 2c/3). The primary outcome was good functional outcome as defined by a 90-day modified Rankin Scale (mRS) 0-2. The primary study exposure was first pass success (FPS, 1 pass vs ≥2 passes) and the secondary exposure was PT. Logistic regression models were fit-adjusted and marginal effects used to assess the interaction of PT (≤30 vs >30 minutes) and FPS, adjusting for potential confounders including time from last known well to start of MT. Results: A total of 1,310 patients had excellent reperfusion. These patients were divided into two cohorts based on PT: ≤30 minutes (777 patients, 59.3%) and > 30 minutes (533 patients, 40.7%). Good functional outcome was observed in 658 patients (50.2%). The interaction term between FPS and PT was significant (p=0.018). Individuals with FPS in ≤30 minutes had 11.5% higher adjusted predicted probability of good outcome compared with those who required ≥2 passes (58.2% vs. 46.7%, p=0.001). However, there was no significant difference in the adjusted predicted probability of good outcome based on FPS in individuals with PT >30 minutes (p=0.763). This relationship appeared identical in models with PT treated as a continuous variable. Conclusion: In a large, real-world, multi-national dataset, we find that FPE is importantly modified by PT. The added clinical benefit of FPE is lost in longer procedures (>30 minutes). These data argue for a new metric for MT procedures, namely, FPE 30 , that better represents the ideal of fast, complete reperfusion with a single pass of a thrombectomy device.