Dyslipidemia: The Role of Non-HDL Cholesterol, Apolipoprotein B and Small, Dense LDL

Abstract

Elevated low-density lipoprotein cholesterol (LDL-C) has traditionally been considered as an independent risk factor for coronary artery disease (CAD). A level of LDL-C< 70 mg/dl is recommended for very high risk individuals. However, it has recently been suggested that the threshold for atherosclerosis may be much lower and it is widely accepted that even with the intense use of statins, not all cardiovascular adverse events are prevented. Consequently, new indexes have emerged that could outperform LDL-C especially in the highest risk populations, such as patients with diabetes type II or the metabolic syndrome. Non- HDL cholesterol is defined as all of the cholesterol that is not HDL (total cholesterol- HDL cholesterol). It has been shown that for each LDL-C category, according to NCEP- Adult Treatment Panel III, an increase in non-HDL cholesterol increased the risk for cardiovascular disease. It seems that the combination of a high concentration of triglyceride- rich particles and LDL-C carries a particularly high risk and increasing VLDL and IDL concentrations add to the risk at any LDL concentration. Total apo-B level reflects the total number of apo- B lipoproteins and measures the total atherogenic particle number. It seems that apo-B levels are much more closely related to the risk of vascular events than LDL-C or non-HDL cholesterol as presented in many large prospective trials. There are at least seven distinct subclasses of LDL of different particle sizes and several recent studies have suggested that LDL subfraction distribution, especially the presence of increased levels of small, dense LDL particles, aid in the prediction of cardiac heart disease risk. Further studies will clarify the clinical circumstances that justify lipoprotein analysis and how to best use the information taken from new indices such as non-HDL, apolipoprotein B or small dense LDL particles, in the management of our patients.