Thrombolysis in Patients With Mild Stroke: Results From the Austrian Stroke Unit Registry

Background and Purpose— Apart from missing the approved time window of 4.5 hours, one frequent cause for withholding recombinant tissue plasminogen activator (rt-PA) treatment in patients with ischemic stroke is presentation with mild deficit on admission. We analyzed in a large cohort of patients whether rt-PA treatment is beneficial for this group of patients. Methods— From a total of 54 917 patients with ischemic stroke prospectively enrolled in the Austrian Stroke Unit Registry, 890 patients with mild deficit defined as ⩽5 points in the National Institutes of Health Stroke Scale treated with and without rt-PA were matched for age, sex, prestroke disability, stroke severity, hypertension, diabetes mellitus, hypercholesterolemia, stroke cause, and clinical stroke syndrome. Functional outcome was assessed using the modified Rankin Scale at 3 months. For data visualization, weighted averages of outcome differences were computed for all age severity combinations and mapped to a color. For quantification of effect sizes, numbers need to treat were calculated. Results— rt-PA–treated patients with mild deficit had a better outcome after 3 months compared with matched cases without rt-PA treatment (odds ratio [OR], 1.49; 95% confidence interval [CI], 1.17–1.89; P<0.001). In rt-PA–treated patients with mild deficit, the numbers need to treat ranged from 8 to 14. Improvement achieved by rt-PA treatment was observed along the entire age range. Conclusions— In our study, intravenous rt-PA treatment was beneficial for patients with mild deficit. Given the observational nature of these results, our data might serve as an incentive for future randomized controlled trials to provide a basis for optimal patient selection.