Determinants and Outcomes of Asymptomatic Intracranial Atherosclerotic Stenosis.

ABSTRACT

BACKGROUND: Intracranial 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. OBJECTIVES: This study identified the role of risk factors and risk of vascular events in subjects with asymptomatic ICAS for improved risk stratification. METHODS: Stroke-free participants in the NOMAS (Northern Manhattan Study) trial, 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. RESULTS: The 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% CI1.4 to 3.2; compared with those with no ICAS). CONCLUSIONS: ICAS 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.