What is Dyslipidaemia ?
The results of epidemiological studies, as well as trials with angiographic or clinical endpoints, confirm the importance of various lipid fractions in the pathogenesis of atherosclerosis. There is a strong and graded positive association between total and LDL cholesterol and risk of vascular events (mainly ischaemic heart disease) extending over a wide range of cholesterol concentrations. This association applies to individuals with or without established CAD as well as to women and men. Other risk factors can substantially aggravate the effects of LDL cholesterol.
The other fraction of the lipid is HDL cholesterol. It is also called 'good' cholesterol as there is a strong and inverse association between HDL cholesterol and the risk of CAD in both men and women and in subjects with or without established CAD; the lower the concentration of HDL-cholesterol the greater the risk of CAD. The inverse association between HDL-cholesterol levels and CAD risk at least equals the positive association between CAD risk and serum LDL cholesterol events. There is now evidence from the Veterans Administration High density Lipoprotein Cholesterol Intervention Study (VA-HIT) that the increase in HDL-cholesterol in CAD patients is followed by a significant decrease in major coronary events.
Triglycerides are the other lipid components in the blood 2nd they also contribute to an increased risk of coronary artery disease by a number of mechanisms. The triglyceride rich lipoproteins may be independently atherogenic or they may promote atherosclerosis by inducing a procoagulant state and promoting thrombosis.
While level of individual lipid factor may be important in the pathogenesis of coronary atheroclerosis, interplay of different lipid fractions is much more significant. For example, at a given level of LDL cholesterol, the atherogenic potential is enhanced in presence of low HDL cholesterol level. Again, the ratio of total cholesterol (TC) to HDL cholesterol (HDLc) emerges as the most powerful predictor of atherosclerosis; a TC/HDLc ratio more than 4,5 is associated with high risk of CAD.