The Metabolic Cardiovascular Syndrome: Syndrome X, Reavenʼs Syndrome, Insulin Resistance Syndrome, Atherothrombogenic Syndrome

Summary: A short review of the metabolic cardiovascular risk syndrome (MCVS) is given. Traditionally, cardiovascular risk has been associated with three so-called “main” risk factors: hypercholesterolemia, hypertension, and smoking. In addition, the association between diabetes and cardiovascular disease has been known for many years in clinical medicine. Primarily, these risk factors have been regarded separately as independent factors, although epidemiological studies showed intercorrelations between them. However, it is now well accepted that relatively few at-risk individuals have only one risk factor, and in many cases a whole “symphony” of factors play together to create what we might call an individuals' risk profile. As an example, very often essential hypertension has been regarded as a disease in itself, which can be successfully treated just by lowering the blood pressure by drugs. When such a strategy obviously failed, the association of elevated blood pressure with dyslipoproteinemia and impaired glucose tolerance attracted more attention, particularly when it was realized that many antihypertensive drugs affected risk in MCVS in a possible negative way. The most important etiologic factor of MCVS is (besides genetics) an excessive caloric intake compared to what the individual spends in physical activity. In the clinical setting, the most important findings of MCVS are central obesity, dyslipoproteinemia with low high-density lipoprotein (HDL) cholesterol, hypertension, reduced insulin sensitivity in peripheral tissues, and increased thrombogenicity. The reduced insulin sensitivity leads to a compensatory increase in β-cell insulin production, and thereby hyperinsulinemia. Hypertension develops, probably due in part to the hyperinsulinemia, which also has unwanted effects on the plasma lipoprotein profile with increased levels of triglycerides, especially postprandial, reduced HDL cholesterol, and increased thrombogenicity with impaired fibrinolytic capacity, increased level of certain coagulation factors, and probably also unwanted effects on platelet function. It has not been until recent years that increased thrombogenicity was recognized as an integral part of MCVS, but this part of the syndrome is probably particularly important, as the morphological “result” in, for instance, coronary occlusion in most cases consists not only of atheroclerosis, but also thrombosis. Consequently, a more logical designation of the MCVS would be the “atherothrombogenic syndrome” (ATS). The treatment of this risk syndrome consists mainly of lifestyle modifications, the most important being changes in dietary and exercise habits. In many cases, it is equally important to avoid drug-induced hypo-HDL-emia and hypertriglyceridemia. These intervention measures are of crucial importance in the strategy of preventive cardiology, in the prevention of drug-dependent hypertension, and type II diabetes mellitus.