Thrombus Burden Is Associated With Clinical Outcome After Intra-Arterial Therapy for Acute Ischemic Stroke

Abstract

Background and Purpose— Studies have established a relation between recanalization and improved clinical outcome in acute ischemic stroke patients; however, intra-arterial clot size has not been routinely assessed. The aim of the study was to determine the impact of intra-arterial thrombus burden on intra-arterial treatment (IAT) and clinical outcome. Methods— A retrospective review of our IAT stroke database included procedure time, recanalization, symptomatic intracranial hemorrhage, poor outcome (modified Rankin Scale score ≥4 at discharge), and mortality. The modified Thrombolysis in Myocardial Infarction thrombus grade was dichotomized into grades 0 to 3 (no clot or moderate thrombus, 2 vessel diameters). Results— Data were collected on 135 patients with thrombus grading. The baseline median National Institutes of Health Stroke Scale score was higher in patients of grade 4 compared with grades 0 to 3 (19 vs 17, P =0.012). Grade 4 thrombi required longer (median, range) times for IAT (113, 37 to 415 minutes vs 74, 22 to 215 minutes, respectively; P P =0.005). There were no differences in rates of symptomatic intracranial hemorrhage (6.6% vs 4.1%, P =0.701) or recanalization (50% vs 61%, P =0.216) in grade 4 versus grades 0 to 3. Multivariate analysis adjusted for age, baseline National Institutes of Health Stroke Scale score, and artery of involvement showed that grade 4 thrombi were independently associated with poor outcome (odds ratio=2.4; 95% CI, 1.06 to 5.57; P =0.036) and mortality (odds ratio=4.0; 95% CI, 1.2 to 13.2; P =0.023). Conclusions— High thrombus grade as measured by the modified Thrombolysis in Myocardial Infarction criteria may be a risk factor that contributes to poor clinical outcome.