First Pass Effect in Patients Undergoing Endovascular Treatment for Posterior Circulation Acute Ischemic Stroke.

Objective: This study aims to investigate the impact of first pass effect (FPE) on outcomes in the posterior circulation acute ischemic stroke (PC-AIS) and the independent predictors of FPE. Methods: This was a multicenter, retrospective study. PC-AIS patients who underwent endovascular treatment were reviewed. The cohort achieving complete or nearly complete reperfusion (defined as expanded treatment in cerebralischemia [eTICI] >= 2c) was categorized into the FPE and multiple pass effect (MPE) groups. FPE was defined as achieving eTICI >= 2c with a single pass and without the use of rescue therapy. Modified FPE (mFPE) was defined as meeting the criteria for FPE but with eTICI >= 2b. The association of FPE with 90-day clinical outcomes and predictors for FPE were both investigated. Results: The study included a total of 328 patients, with 69 patients (21 %) in the FPE group. For primary outcome, FPE had a significant higher favorable outcome (mRS <= 3) rate than MPE (65.2 % vs. 44.8 %, p = 0.003). Similar outcomes were observed in the mFPE. Furthermore, FPE was significantly associated with favorable outcome (adjusted OR 2.23, 95 % CI 1.06-4.73, p = 0.036). Positive predictors for FPE included occlusion in the distal basilar artery, the first-line aspiration or combination, and cardioembolic etiology. Negative predictors for FPE included hypertension and general anesthesia. Conclusion: For PC-AIS patients due to large or medium vessel occlusion, FPE is associated with favorable clinical outcomes. The first-line techniques of aspiration or combination, as well as avoiding general anesthesia, contribute to a better realization of FPE.