Endovascular Stroke Therapy for Posterior Circulation Acute Ischemic Stroke Has Diminishing Benefit with Additional Passes

Background The relationship between pass number during endovascular stroke therapy (EST) and outcomes in anterior circulation large vessel occlusion (LVO) acute ischemic stroke (AIS) has been well studied. However, the association between EST attempts and outcomes for patients with posterior circulation LVO remains unclear. Methods From our prospectively maintained multicenter registry, we identified consecutive patients with LVO AIS who underwent EST. The number of thrombectomy passes and per‐pass reperfusion grades (thrombolysis in cerebral infarction) were recorded prospectively at the time of procedure. The primary outcome was the association of number of EST passes and functional independence (modified Rankin scale 0–2) at 90 days. Secondary outcomes included likelihood of attaining substantial reperfusion (thrombolysis in cerebral infarction 2b‐3). Results Among 894 patients with LVO AIS who underwent EST, median age was 68 [interquartile range 58–78], 49% were female, and median National Institutes of Health Stroke Scale was 16 [interquartile range 11–21]. Of this cohort, 86 (9.6%) had posterior circulation LVO, including 65 (7%) with basilar artery occlusion and 9 (1%) with vertebral artery occlusion. The diminishing benefit on successful reperfusion of additional passes was similar for anterior and posterior circulation AIS. Among patients with posterior circulation stroke, successful reperfusion with fewer passes was associated with greater likelihood of good functional outcome at 90 days (40.0% versus 4.8% modified Rankin scale 0–2 with 1–2 versus 3+ passes; P = 0.003). The likelihood of good outcome in patients with posterior circulation LVO treated with EST and successful reperfusion in 1–2 passes was comparable to patients with anterior circulation LVO (40.0% versus 40.2%, posterior versus anterior; P = 0.553). Conclusions The number of EST passes has a significant association with functional independence at 90 days for patients with posterior circulation LVO AIS. After 2 passes, there is significantly reduced benefit conferred by additional passes. Overall clinical outcomes in patients with successful reperfusion with 1–2 passes were similar in patients with posterior circulation compared with anterior circulation LVO.