The effect of asymptomatic intracranial hemorrhage after mechanical thrombectomy on clinical outcome

Background and objective: Whether asymptomatic intracranial hemorrhage (ICH) affects the clinical outcomes in patients with acute large vessel occlusion treated with mechanical thrombectomy (MT) remains unclear. This study aimed to address this uncertainty. Methods: We retrospectively analyzed patients with acute ischemic stroke and internal carotid or middle cerebral (M1 segment) artery occlusion treated with MT between April 2011 and March 2021 at a single center. All patients had a premorbid modified Rankin scale (mRS) score < 2 and an anterior circulation occlusion and underwent magnetic resonance imaging at admission. Asymptomatic ICH was defined as ICH without symptomatic ICH defined by the SITS-MOST criteria. A favorable outcome was defined as an mRS score < 2 at 90 days after stroke onset. Results: Our study included 349 patients; 62% were men, the median age was 76 [67-83] years, and the median National Institutes of Health Stroke Scale (NIHSS) score was 15 [8-21]. As determined via computed tomography, 103 (30%) patients had ICH (20 symptomatic and 83 asymptomatic). The favorable outcome rate was significantly lower for asymptomatic vs. no ICH (30% vs. 67%, p < 0.01). In a multivariate regression analysis, a high NIHSS score (odds ratio [OR], 1.06; 95% confidence interval [CI], 1.02-1.10; p < 0.01) and low Alberta Stroke Program Early CT Score (OR, 0.78; 95% CI, 0.65-0.92; p < 0.01) were independent risk factors for ICH. Conclusions: Asymptomatic ICH is associated with poor clinical outcome at 90 days after stroke onset.