Lipids, risk factors and ischaemic heart disease

Over 200 risk factors for cardiovascular disease (CVD) have now been identified. Among these, the three most important are (1) abnormal lipids, including the fact that there are more than 15 types of cholesterol-containing lipoproteins and four different types of triglyceride-rich particles, some of which are very atherogenic, (2) high blood pressure, and (3) cigarette smoking. In addition, many other factors including diabetes, haemostatic factors such as fibrinogen, factor VII, plasminogen activator inhibitors, and new factors such as apolipoprotein E4 and homocysteine, are known to increase the risk of developing clinical CVD. A low risk for CVD requires that these various factors are present in the circulation in the correct proportions. Two simple tests for determining plasma lipid levels can be used to identify those individuals with an atherogenic lipid profile and who are, therefore, at increased risk for CVD. Firstly, the ratio of total cholesterol to high density lipoprotein cholesterol (HDL cholesterol) should be determined, followed by measurement of plasma triglyceride concentrations. This will allow differentiation of whether the low density lipoproteins (LDL), HDL cholesterol or triglyceride-rich particles such as the small dense β-very low density lipoproteins (VLDL) are the major cause for concern. Once identified, those individuals with a high lipid risk profile should be treated before, rather than after, experiencing coronary heart disease (CHD).