Risk factor associations with the presence of a lipid core in carotid plaque of asymptomatic individuals using high-resolution MRI: the multi-ethnic study of atherosclerosis (MESA).

BACKGROUND AND
PURPOSE: Atheroma vulnerability to rupture is increased in the presence of a large lipid core. Factors associated with a lipid core in the general population have not been studied.
METHODS: The Multi-Ethnic Study of Atherosclerosis (MESA) is a multicenter cohort study of individuals free of clinical cardiovascular disease designed to include a high proportion of ethnic minorities. We selected MESA participants from the top 15th percentile of maximum carotid intima media thickness by ultrasound and acquired high-resolution black blood MRI images through their carotid plaque before and after the intravenous administration of gadodiamide (0.1 mmol/kg). Lumen and outer wall contours were defined using semiautomated analysis software. We analyzed only plaques with a maximum thickness >or=1.5 mm by MRI (n=214) and assessed cross-sectional risk factor associations with lipid core presence by multivariable logistic regression.
RESULTS: A lipid core was present in 151 (71%) of the plaques. After controlling for age, ethnicity, sex, maximum arterial wall thickness, hypertension, cigarette smoking, diabetes, and C-reactive protein, compared with participants in the lowest tertile of total plasma cholesterol, the ORs of having a lipid core for participants in the middle and highest tertiles were 2.76 (95% CI: 1.01 to 7.51) and 4.63 (95% CI: 1.56 to 13.75), respectively. None of the other risk factors was associated with lipid core.
CONCLUSIONS: In persons with thickened carotid walls, plasma total cholesterol, but not other established coronary heart disease risk factors, is strongly associated with lipid core presence by MRI. High total cholesterol may be associated with rupture proneness of atherosclerotic lesions in the general population.