Alteplase vs. Aspirin in Minor Stroke

Study Questions:

Is intravenous (IV) alteplase (tissue plasminogen activator [tPA]) effective and safe in patients with acute nondisabling ischemic stroke?


PRISMS was a 1:1 randomized, double-blind clinical trial of IV tPA (with oral placebo) compared with aspirin 325 mg (with IV placebo) in patients treated within 3 hours of stroke onset. Patients ≥18 years old with nondisabling acute ischemic stroke and low National Institutes of Health Stroke Scale (NIHSS) scores of 0-5 were enrolled. A stroke was considered nondisabling if there were no deficits that would prevent the patient from performing activities of daily living, walking unassisted, or returning to work. The primary efficacy outcome was the difference between the two groups in favorable outcome (modified Rankin scale score 0-1) at 90 days. The primary safety outcome was any neurologic decline within 36 hours attributed to intracranial hemorrhage (ICH).


The study was terminated early because of slow recruitment after 313 (of planned 948) patients were enrolled. The mean age was 62 (± 13) years and the median NIHSS was 2 (interquartile range, 1-3). Final diagnosis was acute ischemic stroke in 87% and neurovascular mimic in 13%. At 90 days, 122 of 156 (78.2%) in the IV tPA group and 128 of 157 (81.5%) in the aspirin group had a favorable outcome (p > 0.05). Within 36 hours of treatment, 5 of 156 (3.2%) in the IV tPA group compared to 0 of 157 (0%) in the aspirin group had symptomatic ICH (risk difference, 3.3%; 95% confidence interval, 0.8%-7.4%); none of the symptomatic ICH patients died.


In this study, IV tPA was neither effective nor safe in patients with acute nondisabling ischemic stroke. However, only 33% of the intended study population was enrolled. While these results are interesting and certainly hypothesis-generating, the very early termination of this study prevents any definitive conclusions about the effectiveness and safety of IV tPA in nondisabling stroke.


This study was performed because of uncertainty about whether IV tPA is effective and safe in patients with low NIHSS scores and nondisabling deficits. Because of its early termination, this study does not dramatically lessen this uncertainty. However, because of the nonsignificantly greater proportion of patients with favorable outcome in the aspirin group and the higher incidence of symptomatic ICH in the IV tPA group, the results of this study will likely be used by many stroke providers to justify withholding of IV tPA in acute ischemic stroke patients with nondisabling deficits.

Keywords: Activities of Daily Living, Anticoagulants, Aspirin, Brain Ischemia, Intracranial Hemorrhages, Primary Prevention, Risk, Stroke, Tissue Plasminogen Activator, Treatment Outcome, Vascular Diseases

< Back to Listings