High-density lipoprotein cholesterol, high-density lipoprotein particle size, and apolipoprotein A-I: significance for cardiovascular risk: the IDEAL and EPIC-Norfolk studies.

Description

In order to investigate the relationship between HDL cholesterol levels, HDL particle size, apolipoprotein AI (apo AI) levels, and risk of coronary artery disease (CAD), van der Steeg et al. conducted post-hoc analyses in the IDEAL (Incremental Decrease in End Points Through Aggressive Lipid Lowering) and EPIC (European Investigation into Cancer and Nutrition)-Norfolk studies. Although elevated HDL cholesterol levels were associated with a decreased CAD risk in both studies, high HDL cholesterol levels were found to be associated with an increased CAD risk after adjustment for apo AI and apo B only in the IDEAL study. As for HDL particle size (only measured in EPIC-Norfolk), it was found to have similar associations than for HDL cholesterol. In addition, apo AI levels were inversely associated with CAD, even after adjusting for HDL cholesterol and HDL particle size, which suggests that the cadioprotective effect of HDL cholesterol might be attributable to apoAI rather than HDL cholesterol per se. This paper was accompanied by an editorial by Genest who provided some mechanistic insights to explain the epidemiological findings. He addressed three important questions regarding HDL: 1) Is raising HDL beneficial in terms of cardiovascular health? 2) Does the means by which this increase is achieved matter? 3) Is HDL cholesterol or apo AI the appropriate measurement for therapeutic goals?