Achieving substantial reperfusion in the first pass is a strong predictor of clinical outcomes. Its role in preventing symptomatic ICH (sICH) is incompletely characterized.We assess the association of increasing number of passes with sICH using a large multicenter, prospectively collected international registry with core-lab adjudicated blinded imaging endpoints.We analyzed all patients receiving EVT for LVO in the COMPLETE (Penumbra, Inc) registry. SICH at 24 hours was defined as greater than four-point increase in NIHSS associated with ICH after review by two independent physicians. Multivariable analysis adjusted for age, NIHSS, occlusion location, and ASPECTS were used to assess the likelihood of developing sICH.Among 650 patients included in the analysis, median age was 70 IQR 60–79 and 54% were female. Average number of passes was 1.5. First pass mTICI 2b-3 was achieved in 55.5% (358/645) while 32.2% (208/645) required two or greater attempts. SICH occurred in 25 (3.8%) and PH-2 in 20 (3.1%). We identified an increased likelihood of sICH with increasing number of attempts to achieve TICI 2b or greater (3 vs 1 pass, OR = 3.98 95% CI, 1.05–15.0, and 4 vs 1 pass, OR = 5.04 95% CI, 1.35–18.8). Failure to achieve mTICI 2b or greater (79/645) was associated with increased incidence of sICH compared to first pass reperfusion (OR = 4.66, CI 95%, 1.43–15.1).Achieving substantial reperfusion with the fewest number of thrombectomy attempts was associated with decreasing likelihood of sICH.ReferencesZaidat OO, Castonguay AC, Linfante I, et al. First pass effect: a new measure for stroke thrombectomy devices. Stroke 2018;49(3):660–666. doi:10.1161/STROKEAHA.117.020315Maros ME, Brekenfeld C, Broocks G, et al. Number of retrieval attempts rather than procedure time is associated with risk of symptomatic intracranial hemorrhage. Stroke 2021;52(5):1580–1588. doi:10.1161/STROKEAHA.120.031242DisclosureAll COMPLETE trial investigators received support from Penumbra Inc