Abstract P066: Associations Between Coronary Artery Calcium and HDL Particle Characteristics in MESA Participants with Very-High Levels of HDL Cholesterol (>80mg/dL)

Abstract

Despite the inverse association between HDL-C and CHD risk across HDL-C values of 20-80mg/dL CHD risk persists in people with very-high levels of HDL-C (> 80mg/dL). These risks may be explained by traditional risk factors and by structural and functional polymorphisms in HDL particles in people with HDL-C >80mg/dL. In Multi-Ethnic Study of Atherosclerosis (MESA) participants with HDL-C >80mg/dL we assessed differences in traditional risk factors and NMR-spectroscopy-derived (NMR) HDL particle characteristics between individuals with and without CAC. We included MESA participants with HDL-C values > 80mg/dL (not on niacin, fibrates, or statins), traditional risk factor and CAC data at baseline exam. We examined the associations between HDL-C, NMR data (HDL particle number, particle size, and the concentrations of large, medium and small-HDL particles and in post hoc analysis ratios of particle size concentrations) and baseline CAC > 0 in separate logistic regression models. We included 269 participants in the analysis, 105 had prevalent CAC. Individuals with CAC>0 were older, had higher fasting blood glucose, higher carotid IMT; there were more men, more people taking blood pressure lowering medications, and more with diabetes as well. There were no significant differences in mean values of traditional lipid fractions between groups, however individuals with CAC>0 had a lower concentration of medium-sized HDL particles and a higher ratio of large to medium HDL particle concentration. There were no significant associations between NMR HDL characteristics and CAC> 0 after multivariable adjustment. In post hoc analysis there was a significant adjusted association between the ratio of large to medium sized HDL particle concentration and the presence of CAC>0 (OR [95% CI]: 1.86 [1.15, 3.00]). In conclusion, participants with CAC and very-high HDL-C had a higher burden of traditional risk factors. However, the ratio of particle size concentrations may help differentiate those with HDL>80mg/dL who are at risk for CAC as well.