Abstract P513: Effect of Premorbid Antiplatelet Medication on Infarct Volume at 24 Hours After Late Window Presentation With Anterior Circulation Large Vessel Occlusion

Abstract

Introduction: We sought to evaluate the effect of premorbid antiplatelet medication on 24 hour infarct volume in late presenting patients with anterior circulation large vessel occlusion. Methods: This is a secondary analysis of the DEFUSE 3 trial. The primary outcome is infarct volume on a 24-hour MRI scan (volume of DWI positive tissue). The primary predictor is premorbid use of an antiplatelet medication. We fit linear regression models to 24-hour infarct volume and adjusted for admission infarct volume, age, sex, treatment arm, anticoagulant use, time from stroke onset to presentation, hypoperfusion intensity ratio, tPA administration, admission NIH Stroke Scale, glucose, and systolic blood pressure. In a sensitivity analysis, we included recanalization status in the model (no vs. partial vs. complete recanalization). All models had variance inflation factors <2, indicating acceptable multicollinearity. Results: We included 149 patients, of which 51 (34.2%) took premorbid antiplatelet medication. The mean±SD 24-hour infarct volume was 51.7±50.1 in antiplatelet versus 80.4±93.6 ml in control patients (p=0.04). In the adjusted regression model, taking an antiplatelet medication had a beta coefficient of -31.2 (95% CI, -55.0, -7.4; p=0.011). The other significant predictors of 24-hour infarct volume were admission glucose, baseline infarct volume, and HIR. In the sensitivity analysis with recanalization status in the model (n=132), premorbid antiplatelet use remained associated with 24-hour infarct volume (beta=-29.6, 95% CI -55.8, -3.4, p=0.027). Conclusion: For patients with late window anterior circulation large vessel occlusion stroke, premorbid use of an antiplatelet medication was associated with a ~30 mL smaller 24-hour infarct volume on MRI. Possible explanations for this finding include reduced clot burden, improved clot lysis, the anti-inflammatory effects of antiplatelet medications, or the results could be due to chance.