RT Journal Article SR Electronic T1 Systematic review and meta-analysis of current rates of first pass effect by thrombectomy technique and associations with clinical outcomes JF Journal of NeuroInterventional Surgery JO J NeuroIntervent Surg FD BMJ Publishing Group Ltd. SP 212 OP 216 DO 10.1136/neurintsurg-2020-016869 VO 13 IS 3 A1 Abbasi, Mehdi A1 Liu, Yang A1 Fitzgerald, Seán A1 Mereuta, Oana Madalina A1 Arturo Larco, Jorge L A1 Rizvi, Asim A1 Kadirvel, Ramanathan A1 Savastano, Luis A1 Brinjikji, Waleed A1 Kallmes, David F YR 2021 UL http://jnis.bmj.com/content/13/3/212.abstract AB Background First pass effect (FPE) in mechanical thrombectomy is thought to be associated with good clinical outcomes.Objective To determine FPE rates as a function of thrombectomy technique and to compare clinical outcomes between patients with and without FPE.Methods In July 2020, a literature search on FPE (defined as modified Thrombolysis in Cerebral Infarction (TICI) 2c–3 after a single pass) and modified FPE (mFPE, defined as TICI 2b–3 after a single pass) and mechanical thrombectomy for stroke was performed. Using a random-effects meta-analysis, we evaluated the following outcomes for both FPE and mFPE: overall rates, rates by thrombectomy technique, rates of good neurologic outcome (modified Rankin Scale score ≤2 at day 90), mortality, and symptomatic intracerebral hemorrhage (sICH) rate.Results Sixty-seven studies comprising 16 870 patients were included. Overall rates of FPE and mFPE were 28% and 45%, respectively. Thrombectomy techniques shared similar FPE (p=0.17) and mFPE (p=0.20) rates. Higher odds of good neurologic outcome were found when we compared FPE with non-FPE (56% vs 41%, OR=1.78) and mFPE with non-mFPE (57% vs 44%, OR=1.73). FPE had a lower mortality rate (17% vs 25%, OR=0.62) than non-FPE. FPE and mFPE were not associated with lower sICH rate compared with non-FPE and non-mFPE (4% vs 18%, OR=0.41 for FPE; 5% vs 7%, OR=0.98 for mFPE).Conclusions Our findings suggest that approximately one-third of patients achieve FPE and around half of patients achieve mFPE, with equivalent results throughout thrombectomy techniques. FPE and mFPE are associated with better clinical outcomes.