ObjectiveWhile there is class I evidence for mechanical thrombectomy for anterior circulation large vessel occlusion (LVO) stroke; no high-class evidence exists for the posterior circulation. Multiple retrospective case studies have assessed thrombectomy for posterior circulation LVO but incorporated data before 2015. The authors sought to explore outcomes of post-2015 posterior LVO mechanical thrombectomy.MethodsAcute ischemic stroke patients who underwent mechanical thrombectomy for anterior and posterior large vessel occlusion (LVO) stroke between 02/2016 and 08/2020 from two comprehensive stroke centers were reviewed. Anterior and posterior LVO strokes were compared. Predictors for a favorable outcome (mRS 0-2), death (mRS 6), and futile revascularization (mRS 4-6 despite TICI 2b/3 revascularization) for posterior LVO were analyzed.ResultsCollectively, 813 LVO thrombectomy cases were analyzed, and 77/813 (9.5%) were located in the posterior circulation. While favorable 90-day functional outcome rates did not differ between anterior and posterior LVO, death was significantly more frequent among posterior LVO cases. Posterior, compared to anterior location, independently predicted death in multivariable analysis. In the posterior LVO subgroup, a primary aspiration technique and successful revascularization TICI 2b/3 irrespective of time to the intervention was independently associated with achieving a favorable outcome and preventing death. Higher risk of futile revascularization, however, was independently associated with treatment beyond the six-hour time window.ConclusionPosterior circulation LVO mechanical thrombectomy appears safe and effective in judiciously selected patients. The use of a primary aspiration technique and achieving successful revascularization appear fundamental.Disclosures P. Hendrix: None. M. Killer-Oberpfalzer: None. E. Broussalis: None. I. Melamed: None. S. Pikija: None. C. Hecker: None. O. Goren: None. R. Zand: None. C. Schirmer: None. E. Trinka: None. C. Griessenauer: None.