Pretreatment Diffusion-Weighted Imaging Lesion Volume Predicts Favorable Outcome After Intravenous Thrombolysis With Tissue-Type Plasminogen Activator in Acute Ischemic Stroke

Background and Purpose-Stroke magnetic resonance imaging with perfusion and diffusion weighting has shown its potential to select patients likely to benefit from intravenous thrombolysis with tissue-type plasminogen activator (IV-tPA). We aimed to determine the predictors of favorable outcome in magnetic resonance imaging-selected, acute stroke patients treated with IV-tPA. Methods-We analyzed the data of acute ischemic stroke patients from a prospective, multicenter, observational study of magnetic resonance imaging-based IV-tPA treatment initiated <= 6 hours from symptom onset. Neurologic deficit on admission was assessed by the National Institutes of Health Stroke Scale. Clinical outcome was assessed after 90 days according to the modified Rankin Scale. Favorable outcome was defined as a modified Rankin Scale score of 0 to 1. Patients were compared regarding baseline parameters. Multivariate regression analysis was used to identify predictors of favorable outcome. Results-Of 174 patients, 83 (48%) reached a favorable outcome. They were younger (median age, 62 versus 67 years; P=0.001), had a lower National Institutes of Health Stroke Scale score on admission (median, 11 versus 15; P<0.001), and had smaller diffusion-weighted imaging lesions (median, 12.9 versus 20 mL; P=0.001). Perfusion-weighted imaging lesion volumes and onset-to-treatment time were comparable between the groups. Age (P=0.017), National Institutes of Health Stroke Scale score on admission (P<0.001), and diffusion-weighted imaging lesion volume (P=0.047) were identified as independent predictors of favorable outcome. Conclusions-A lower age, lower National Institutes of Health Stroke Scale score on admission, and smaller pretreatment diffusion-weighted imaging lesion volume were found to be associated with a favorable outcome after treatment with IV-tPA. Pretreatment perfusion lesion volume and onset-to-treatment time were not associated with outcome when patients were selected for IV-tPA by magnetic resonance imaging within 6 hours of symptom onset. (Stroke. 2011;42:1251-1254.)