Abstract 182: Association of High-Degree Intracranial Stenosis With Risk of Vascular Events Among Stroke-Free Individuals: Results From the Northern Manhattan Study (nomas)

Abstract

Background: Individuals with stroke due to high-degree intracranial stenosis (i.e. > 70% by WASID criteria have a high 1-year risk of stroke recurrence. Whether high-degree intracranial stenosis in stroke-free individuals increases the risk of vascular events is less certain. We hypothesized that high-degree intracranial stenosis in stroke-free individuals is associated with risk of death and vascular events. Methods: Participants in the population-based Northern Manhattan Study (NOMAS) with available time-of-flight MRA were included in this study. We rated intracranial stenosis using WASID criteria and defined high-degree intracranial stenosis if the lumen was reduced by > 70% in the anterior, middle, or posterior cerebral arteries or in the basilar, vertebral or intracranial carotid arteries. Death and vascular events were prospectively ascertained, blinded to stenosis status. Stroke outcomes were subtypes according to the Trial of Organon in Acute Stroke Trial (TOAST) criteria. Results: We included 1,206 NOMAS participants (mean age 70.6±9 years, 60.5% women, 65.7% Hispanic). The participants were followed for an average of 10.4 years (IQR 9.5-12.6). The prevalence of high-degree intracranial stenosis was 3.5% (74% isolated anterior circulation, 21% isolated posterior circulation, and 5% anterior and posterior circulation). In univariate analysis, high-degree intracranial stenosis was associated with older age (P=0.003), hypertension (P=0.02) and diabetes (0.02). The risk of vascular death and stroke was higher among stroke-free individuals with high-degree intracranial stenosis (table), and in particular with strokes due to large artery atherosclerosis. Conclusions: Evidence of high-degree intracranial stenosis among stroke-free individuals identifies those at risk of vascular events and may be used to select individuals for testing aggressive measures to reduce vascular risks.