[The "second atherogenic phenotype" or the role of insulin resistance in vascular risk]

LDL cholesterol is the principal vascular risk factor but it is not the only one. Paradoxically, the atherogenic role of triglycerides or that of metabolic abnormalities of triglyceride-rich lipoproteins has been underestimated. It is convenient to use the term "second atherogenic phenotype" for those phenotypes associating a hypertriglyceridaemia, a low HDL-cholesterol, a moderate increase in LDL cholesterol composition (the small dense LDL). Insulin resistance could be the common denominator of these different abnormalities, increasing the production of triglyceride-rich lipoproteins and decreasing their catabolism. In this concept which remains hypothetical, insulin resistance would appear to be a vascular risk factor. Its role could be direct or indirect by the many risk factors described in the syndrome X. The taking into account of this second atherogenic phenotype of hyperlipidaemia has obvious therapeutic implications because of the choice of diet and treatment. Though stains represent the treatment of choice of high LDL cholesterol, the fibrates are useful in the treatment of hypertriglyceridaemia, low HDL-cholesterol and small and dense LDL. Therapeutic trials comparing the efficacy of statins and fibrates with respect to cardiovascular and global mortality should provide future information in this debate.