Abstract
Background:
Asymptomatic internal carotid artery (ICA) stenosis is a modifiable risk factor for ischemic stroke but its role in subclinical brain infarction (SBI), also a stroke risk factor, is poorly understood especially in multiethnic populations.
Methods:
In the Northern Manhattan Study community-based cohort, stroke-free participants underwent quantitative assessment of SBI with MRI and of carotid atherosclerosis with Doppler ultrasound. We examined the prevalence and location of SBI in those with and without carotid stenosis (defined as ≥60% or occlusion). We used Fisher Exact Tests to assess group differences.
Results:
The mean age of the sample (N=1217) was 71±9 years and 60% were women. The race-ethnic distribution was 65% Hispanic white, 18% non-Hispanic Black, and 17% non-Hispanic white. There were 21 participants with asymptomatic ICA stenosis or occlusion (1.7%) and 170 participants with SBI (14%). Overall, five of 21 participants with ICA stenosis or occlusion had SBI (24%) compared to 165 of 1196 with less or no stenosis (14%), but this difference was not statistically significant (Fisher Exact Test P=0.19). However, a greater proportion of participants with stenosis or occlusion had cortical SBI (N=3 of 21, 14%) compared to those with less or no stenosis (N=28 of 1196, 2%; Fisher Exact Test P=0.03). Also, of five participants with both SBI and stenosis or occlusion, four were ipsilateral and one was contralateral to the lesion. Race/ethnic differences were not discernible.
Conclusions:
In this stroke free community based sample, participants with asymptomatic ICA stenosis had a greater proportion of cortical SBI than those with less or no stenosis. Further studies with larger race/ethnically diverse samples are needed to confirm these findings, and to assess the risk of stroke associated with having both asymptomatic carotid atherosclerosis and SBI.