Abstract W P120: Effect of Prior Aspirin Use on Initial Stroke Severity and Hemorrhagic Transformation

Abstract

Background and Purpose: The effect of prior aspirin use on the severity and safety of index ischemic stroke have not been well investigated. We studied the effect of prior aspirin use on initial stroke severity and also on the hemorrhagic transformation in initial MRI. Methods: Using a prospective multicenter stroke registry, patients who were hospitalized due to ischemic stroke and had relevant lesions on MRI were selected. Patients who were on anticoagulants or whose stroke subtype was categorized as stroke of other determined etiology or undetermined etiology were excluded. Baseline stroke severity was measured using the NIHSS scores at presentation, and was compared between no prior aspirin (non-PA) users and prior aspirin (PA) users with stratification by stroke subtypes. Prevalence of the hemorrhagic transformation in initial GRE-MRI was also compared between those two groups. Results: Among the 11,183 patients, a total of 2,664 (23.2%) patients reported use of an aspirin within a week of stroke onset. In crude analysis, the overall baseline NIHSS score was lower in non-PA group than PA group (5.69 vs. 6.08, P=0.005). The interaction between prior aspirin use and stroke subtype was significant (P = 0.031) in a multivariable analysis. When the study subjects were stratified by stroke subtype, the baseline NIHSS in PA groups was significantly lower in large artery atherothrombosis group (5.77 vs. 5.21, P=0.001), but not in those with cardioembolism as well as small-vessel occlusion before and after adjustments. Hemorrhagic transformation in initial GRE-MRI was more frequently observed in PA groups (4.3% vs. 7.6%, P<0.001) irrespective of stroke subtypes. Conclusions: Our study suggests that the reduction of initial stroke severity in the prior aspirin users may differ by stroke mechanism, which was only significant in patients with large artery atherothrombotic stroke.