Prevalence of Intracranial Atherosclerotic Stenosis Using High Resolution Magnetic Resonance Angiography in the General Population – The ARIC Study

Abstract

Background and Purpose

Intracranial atherosclerotic stenosis (ICAS) is a common cause of stroke, but little is known about its epidemiology. We studied the prevalence of ICAS and its association with vascular risk factors using high resolution magnetic resonance angiography (MRA) in a U.S. cardiovascular cohort.

Methods

The Atherosclerosis Risk in Communities (ARIC) study recruited participants from four U.S. communities from 1987-1989. Using stratified sampling, we selected 1980 participants from visit-5 (2011-2013) for high resolution 3T-MRA. All images were analyzed in a centralized lab and ICAS was graded as — no stenosis, <50% stenosis, 50-69% stenosis, 70-99% stenosis and complete occlusion. We calculated per-vessel and per-person prevalence of ICAS (weighted for n=6,538 visit-5 participants), and also estimated the U.S. prevalence. We used multivariable logistic regression to identify variables independently associated with ICAS.

Results

Subjects who had an adequate MRA (n=1765) were aged 67-90 years, 41% were men, 70% were white and 29% were African-American. ICAS was prevalent in 31% of participants and 9% had ICAS ≥50%. Estimated U.S. prevalence of ICAS≥50% for 65-90 years old was 8% for Whites and 12% for African-Americans. Older age, African-American race, higher systolic blood pressure, and higher low density lipoprotein cholesterol levels were associated with increased odds of ICAS, while higher levels of high density lipoprotein cholesterol and use of cholesterol lowering medications were associated with decreased odds of ICAS. Body mass index and smoking were not associated with ICAS.

Conclusion

The prevalence of ICAS in older adults is high, and could be a target for primary prevention of stroke and dementia in this population.