First pass effect in patients with large core infarcts undergoing mechanical thrombectomy: subgroup analysis of the prospective international ASSIST registry

BACKGROUND: Studies have described a first pass effect (FPE) where patients with successful recanalization after one pass experience better outcomes. Few studies have evaluated this in patients with large core infarctions. OBJECTIVE: To determine whether patients with large core infarcts undergoing mechanical thrombectomy in which first pass reperfusion is achieved experience improved outcomes compared with those who undergo more than one pass. METHODS: The ASSIST Registry, a prospective, global, multicenter registry of patients with anterior circulation large vessel occlusion (LVO) undergoing mechanical thrombectomy was used. Adults with internal carotid artery/M1/M2 occlusions and preprocedural Alberta Stroke Program Early CT Score (ASPECTS) <6 were included. The variable of interest was number of thrombectomy passes (dichotomized to 1 or >1) performed for the target occlusion. The primary outcome was 90-day good functional outcome defined as modified Rankin Scale (mRS) score 0-3. RESULTS: 150 patients with a mean age of 66 years were included. Most patients had ASPECTS of 4 (33%) or 5 (59%). 77 patients (51%) underwent one pass. Compared with patients with one pass, those with more than one pass had significantly lower odds of good functional outcome (OR=0.44, 95% CI 0.21 to 0.93; P=0.03). More than one pass was not significantly associated with 90-day mRS score 0-2 (OR=0.46, 95% CI 0.15 to 1.43; P=0.17) or mortality (OR=2.03, 95% CI 0.81 to 5.08; P=0.13). FPE (one pass eTICI≥2c) and modified FPE (one pass extended thrombolysis in cerebral infarction ≥2b50) were not significantly associated with 90-day mRS 0-3, mortality, or symptomatic intracranial hemorrhage. CONCLUSION: This analysis suggests that use of multiple passes is associated with worse outcomes in patients with large core infarcts.