MRI-Based and CT-Based thrombolytic therapy in acute stroke within and beyond established time windows -: An analysis of 1210 patients

Background and Purpose-The use of intravenous thrombolysis is restricted to a minority of patients by the rigid 3-hour time window. This window may be extended by using modern imaging-based selection algorithms. We assessed safety and efficacy of MRI-based thrombolysis within and beyond 3 hours compared with standard CT-based thrombolysis. Methods-Five European stroke centers pooled the core data of their CT-and MRI-based prospective thrombolysis databases. Safety outcomes were predefined as symptomatic intracranial hemorrhage and mortality. Primary efficacy outcome was a favorable outcome (modified Rankin Scale 0 to 1). We performed univariate and multivariate analyses for all end points, including age, National Institutes of Health Stroke Scale, treatment group (CT < 3 hours, MRI < 3 hours and > 3 hours), and onset to treatment time as variables. Results-A total of 1210 patients were included (CT < 3 hours: N = 714; MRI < 3 hours: N = 316; MRI < 3 hours: N = 180). Median age, National Institutes of Health Stroke Scale, and onset to treatment time were 69, 67, and 68.5 years (P = 0.66); 12, 13, and 14 points (P = 0.019); and 130, 135, and 240 minutes (P < 0.001). Symptomatic intracranial hemorrhage rates were 5.3%, 2.8%, and 4.4% (P = 0.213); mortality was 13.7%, 11.7%, and 13.3% (P = 0.68). Favorable outcome occurred in 35.4%, 37.0%, and 40% (P = 0.51). Age and National Institutes of Health Stroke Scale were independent predictors for all safety and efficacy outcomes. The overall use of MRI significantly reduced symptomatic intracranial hemorrhage (OR: 0.520, 95% CI: 0.270 to 0.999, P = 0.05). Beyond 3 hours, the use of MRI significantly predicted a favorable outcome (OR: 1.467; 95% CI: 1.017 to 2.117, P = 0.040). Within 3 hours and for all secondary end points, there was a trend in favor of MRI-based selection over standard < 3-hour CT-based treatment. Conclusion-Despite significantly longer time windows and significantly higher baseline National Institutes of Health Stroke Scale scores, MRI-based thrombolysis is safer and potentially more efficacious than standard CT-based thrombolysis.