Early stroke risk after transient ischemic attack among individuals with symptomatic intracranial artery stenosis

Background: Little is known about short-term vascular risk after transient ischemic attack (TIA) caused by intracranial atherosclerosis. Objectives: To quantify the early risk of ischemic stroke in the territory of a stenotic intracranial artery after TIA and to identify clinical and imaging features associated with increased risk of stroke in the territory among patients with TIA. Design: Cohort study. Setting: Academic research. Patients: The Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) study enrolled patients having TIA or nondisabling stroke within the preceding 3 months and demonstrating corresponding 50% to 99% stenosis of a major intracranial artery on angiography. Main Outcome Measures: We calculated the cumulative risk of stroke in the territory of the symptomatic artery during the first 90 days after randomization among patients having TIA alone as a qualifying event compared with patients having stroke alone. We assessed factors for association with stroke among patients having TIA as the qualifying event. Results: The 90-day risk of ischemic stroke in the arterial territory was 6.9% (95% confidence interval, 4.2%-11.2%) after TIA compared with 4.7% (95% confidence interval, 2.7%-8.4%) after stroke (P=. 32). Among patients having TIA alone as the qualifying event, 60.0% (15 of 25) of all strokes in the arterial territory occurred in the first 90 days compared with 34.4% (11 of 32) among patients having stroke alone as the qualifying event (P=. 05). Among subjects with TIA, the presence of cerebral infarct on baseline neuroimaging was the only statistically significant predictor of higher risk of early stroke (hazard ratio, 4.7; 95% confidence interval, 1.4-15.5; P=. 006). Conclusions: Among individuals having intracranial atherosclerotic disease with TIA, most subsequent strokes in the territory of a stenotic intracranial artery occur early (ie, <= 90 days). Prompt management of TIA in patients having intracranial stenosis, particularly those demonstrating cerebral infarction on brain imaging, is indicated.