[Abdominal obesity and coronary heart disease. Pathophysiology and clinical significance].

The relationship between overweight and cardiovascular disease was a matter of debate for many years. Recent studies have demonstrated that obesity defined as body mass index of 30 kg/m2 or higher is associated with an exponential increase of cardiovascular complications. This effect is largely mediated by the induction of established risk factors such as dyslipidemia, hypertension and type 2 diabetes mellitus. Recently, there is growing evidence that the occurrence of most complications of obesity depends not only on the degree of overweight but also on the pattern of body fat distribution. Many data suggest that the anatomical localization of body fat is more important for the risk of developing complications than the adipose tissue mass per se. An abdominal, upper-body type of fat distribution, which can be easily determined by the measurement of waist and hip circumferences (waist/hip ratio = WHR), is also a confirmed risk factor for metabolic disturbances, hypertension and atherosclerosis, independent of body weight. However, the clinical appearance of these disturbances is frequently associated with the development of obesity. This network of metabolic disorders and their vascular complications is termed "metabolic syndrome" or "syndrome X" (Table 2). Abdominal obesity is now known to be closely associated with the metabolic syndrome and is regarded to represent its readily recognizable phenotypic feature. The components of the metabolic syndrome are characterized by varying forms and degrees of insulin resistance. It is assumed that insulin resistance, defined as diminished biological response to the action of insulin, represents the primary defect or at least the common pathogenetic link between these disturbances.(ABSTRACT TRUNCATED AT 250 WORDS)