Correlates of carotid plaque presence and composition as measured by MRI: the Atherosclerosis Risk in Communities Study.

BACKGROUND: The composition of atherosclerotic plaque affects the likelihood of an atherothrombotic event, but prospective studies relating risk factors to carotid wall and plaque characteristics measured by MRI are lacking. We hypothesized that traditional risk factors are predictors of carotid wall and plaque characteristics measured 2 decades later. METHODS AND
RESULTS: A high-resolution contrast-enhanced MRI examination of the carotid artery was performed in 1769 participants. Measures of carotid wall volume and maximum thickness; lipid core presence, volume and maximum area; and fibrous cap thickness were performed centrally. The sample was, on average, 70 years of age, 57% female, 81% white, and 19% black. Greater age, total and low-density lipoprotein cholesterol, male sex, white race, diabetes, hypertension, and smoking as measured at baseline were all significant predictors of increased wall volume and maximum wall thickness 18 years later. An analysis of lipid core was restricted to the 1180 participants with maximum wall thickness >/=1.5 mm. Lipid core was observed in 569 individuals (weighted percentage, 42%). Baseline age and total and low-density lipoprotein cholesterol were predictors of presence of lipid core 18 years later; however, these relationships were attenuated after adjustment for wall thickness. Concurrently measured low-density lipoprotein cholesterol was associated with greater lipid core volume, independent of wall thickness. Concurrently measured glucose and body mass index were inversely associated fibrous cap thickness.
CONCLUSIONS: Traditional atherosclerosis risk factors are related to increased wall volume and wall thickness 2 decades later, but they do not discriminate characteristics of plaque composition (core and cap) independent of wall size.