Determinants and Outcomes of Asymptomatic Intracranial Atherosclerotic Stenosis

Abstract

BackgroundIntracranial atherosclerotic stenosis (ICAS) is one of the most common causes of stroke worldwide and confers a high risk of stroke recurrence, despite aggressive management of risk factors. ObjectivesThis study identified the role of risk factors and risk of vascular events in subjects with asymptomatic ICAS for improved risk stratification. MethodsStroke-free participants in the NOMAS (Northern Manhattan Study), prospectively followed since 1993, underwent a brain magnetic resonance angiogram from 2003 to 2008. The study rated stenosis in 11 brain arteries as: 0: no stenosis; 1: <50% or luminal irregularities; 2: 50%-69%; and 3: ≥70% stenosis or flow gap. The study ascertained vascular events during the post-magnetic resonance imaging (MRI) period. Proportional odds regression quantified the association of pre-MRI exposures, and proportional hazard adjusted models were built to identify the risk of events in the post-MRI period. ResultsThe included sample included 1,211 participants from NOMAS (mean age: 71 ± 9 years; 59% women; 65% Hispanic; 45% had any stenosis). Older age (OR: 1.02 per year; 95% CI: 1.01 to 1.04), hypertension duration (OR: 1.01 per year; 95% CI: 1.00 to 1.02), higher number of glucose-lowering drugs (OR: 1.64 per each medication; 95% CI: 1.24 to 2.15), and high-density lipoprotein (OR: 0.96 per mg/dL; 95% CI: 0.92 to 0.99) were associated with ICAS. The highest event risk was noted among participants with ICAS ≥70% (5.5% annual risk of vascular events; HR: 2.1; 95% CI:1.4 to 3.2; compared with those with no ICAS). ConclusionsICAS is an imaging marker of established atherosclerotic disease in stroke-free subjects, and incidental diagnosis of ICAS should trigger a thorough assessment of vascular health.