Triglycerides, High-Density Lipoprotein Cholesterol, and Risk of Ischemic Heart Disease: A View from the Copenhagen Male Study

The role of lipids and lipoproteins as important risk factors of ischemic heart disease (IHD) is well established. With the demonstration in large-scale randomized clinical trials that aggressive lowering of low-density lipoprotein (LDL) cholesterol levels with statins reduced the risk of IHD, the central role of LDL cholesterol in the pathogenesis of IHD was proven. However, many IHD cases occur in people with normal LDL cholesterol levels, and it is well known that the ability to predict who will develop IHD based on LDL cholesterol levels alone is limited. Plasma triglycerides and high-density lipoprotein (HDL) cholesterol are two other lipid variables that over the years have attracted attention in cardiovascular epidemiology. Recently, much more attention has been paid to the relationship between triglycerides, HDL cholesterol, and risk of IHD because the combined lipid profile of a high fasting triglyceride level and a low HDL cholesterol level is the characteristic dyslipidemia in the metabolic syndrome X. The objective of the present review article is to use data from the Copenhagen Male Study to demonstrate that, in men, fasting hypertriglyceridemia is a strong risk factor of IHD independent of other major risk factors of IHD, and that the combined lipid profile of a high fasting triglyceride level and a low HDL cholesterol level, the characteristic dyslipidemia in the metabolic syndrome X, is a very strong and important risk factor of IHD, at least as strong and important as a high LDL cholesterol level.