UC Davis

Background

The effects of white matter hyperintensity volume and subclinical brain infarcts on the risk of incident stroke, its ischemic subtypes, and mortality require further study in diverse samples.

Methods and results

Stroke-free participants in the Northern Manhattan Study underwent magnetic resonance imaging (N=1287; mean age 71±9 years, 60% women, 15% non-Hispanic white, 17% non-Hispanic black, 68% Hispanic) and were followed for a median of 8 years (interquartile range: 6-9 years). Cox models estimated proportional hazards of incident stroke of all types, ischemic stroke (and its subtypes), and mortality and stratified by race/ethnicity. In total 72 participants (6%) had incident strokes and 244 died (19%). In fully adjusted models, those with larger white matter hyperintensity volume had greater risk of all stroke types (hazard ratio [HR]: 1.4; 95% CI, 1.1-1.9), ischemic stroke (HR: 1.3; 95% CI, 1.0-1.8), and cryptogenic stroke (HR: 2.2; 95% CI, 1.1-4.4). White and black but not Hispanic participants had increased stroke risk (P<0.05 for heterogeneity for all and ischemic stroke). Those with subclinical brain infarct had greater risk for all stroke types (HR: 1.9; 95% CI, 1.1-3.3), ischemic stroke (HR: 2.2; 95% CI, 1.3-3.8), lacunar (HR: 4.0; 95% CI, 1.3-12.3), and cryptogenic stroke (HR: 3.6; 95% CI, 1.0-12.7), without significant heterogeneity across race/ethnic groups. Greater white matter hyperintensity volume increased both vascular (HR: 1.3; 95% CI, 1.1-1.7) and nonvascular (HR: 1.2; 95% CI, 1.0-1.5) mortality among Hispanic and white but not black participants (P=0.040 for heterogeneity). Subclinical brain infarct was associated with increased vascular mortality among Hispanic participants only (HR: 2.9; 95% CI, 1.4-5.8).

Conclusions

In this urban US sample, subclinical cerebrovascular lesions increased the risk of clinical stroke and vascular mortality and varied by race/ethnicity and lesion type.