The major lipoprotein types, very low-density lipoprotein (VLDL), low-density lipoprotein (LDL), and high-density lipoprotein (HDL), are composed of many subgroups (1–3). Classifications are based on size (1), density, or apolipoprotein (apo) content (2), or a combination of these (3), and the subfractions that are isolated have distinct metabolic and other functional properties. Thus, it is entirely reasonable to think that subfractions of the major lipoproteins have diverse relationships to coronary heart disease (CHD). Because the classical lipid risk factors by no means perfectly predict CHD in patients, lipoprotein subfractionation has the potential to improve risk prediction.
