Peri-procedural decrease in hemoglobin following mechanical thrombectomy for ischemic stroke

Background Peri-procedural blood loss and hemodilution occur in patients undergoing mechanical thrombectomy (MT) for ischemic stroke; however, its relationships with thrombectomy passes, procedure times, and clinical outcomes are unknown.Methods Consecutive patients undergoing MT for anterior circulation large-vessel occlusion ischemic strokes were identified at a Comprehensive Stroke Center. Clinical information, modified treatment in cerebral ischemia (mTICI) scores, and modified Rankin Scores (mRS) at 90 days were prospectively collected from 2012 to 2021. Hemoglobin measurements before and after MTs were collected retrospectively via chart review, and changes were quantified. Patients with new-onset severe anemia (defined as post-MT hemoglobin less than 10g/dL) were identified. Modified Rankin scale (mRS) at 90 days was used to measure clinical outcomes.Results Four-hundred and forty-five patients were identified. Hemoglobin decreased 1.27 +/- 1.05 g/dL after MT on average. Greater number of thrombectomy passes and longer procedure times were associated with larger decreases in hemoglobin (p < 0.001 and p = 0.002, respectively). 11.5% (51 of 445) of patients had new-onset severe anemia, and this incidence was significantly higher with more thrombectomy passes (6.4% for one pass, 11.9% for two passes, and 17.4% for three or more passes; p = 0.010). In multivariable analyses, new-onset severe anemia was associated with significantly higher odds of 90-day poor outcomes (mRS 3-6, OR 2.70 [95%CI 1.12-6.51], p = 0.027) and death (OR 2.73 [95%CI 1.06-7.04], p = 0.037) compared to mild post-MT anemia.Conclusions More thrombectomy passes and longer procedure times were significantly associated with larger peri-procedural decreases in hemoglobin. Patients with new-onset hemoglobin less than 10 g/dL are at risk of poor outcomes.