Obésité et maladies cardiovasculaires

Abstract

Parmi les populations vivant dans les pays industrialisés, un nombre croissant d’individus sont affectés par un surplus de poids dû à leur mode de vie. Ainsi, l’obésité est en voie de devenir le problème de santé le plus commun du XXIesiècle, qui va également contribuer à augmenter de façon importante la prévalence des maladies cardiovasculaires dans les pays en voie de développement. L’obésité est un facteur susceptible d’intervenir dans de nombreuses maladies : maladies cardiovasculaires, diabète, hypertension artérielle, accidents vasculaires cérébraux, embolies pulmonaires, certains cancers, ostéoarthrite, affections de la vésicule biliaire, anomalies respiratoires, dont notamment l’apnée du sommeil. Le fait que l’obésité abdominale soit associée à de nombreuses altérations lipidiques, thrombotiques et inflammatoires laisse penser que le cardiologue sera confronté à d’autres étiologies que le tabagisme et l’hypercholestérolémie.

Available evidence clearly indicates a rapid progression in the prevalence of obesity worldwide. As a consequence, there has also been a marked increase in the prevalence of type 2 diabetes all over the world and this chronic metabolic disease is now considered as a coronary heart disease risk equivalent. However, even in the absence of the hyperglycaemic state which characterizes type 2 diabetic patients, non diabetic individuals with a specific form of obesity, named abdominal obesity, often show clustering metabolic abnormalities which include high triglyceride levels, increased apolipoprotein B, small dense low dendity lipoproteins and decreased high density lipoproteins-cholesterol levels, a hyperinsulinemic-insulin resistant state, alterations in coagulation factors as well as an inflammatory profile. This agglomeration of abnormalities has been referred to as the metabolic syndrome which can be identified by the presence of three of the five following variables : abdominal obesity, elevated triglyceride concentrations, low HDL-cholesterol levels, increased blood pressure and elevated fasting glucose. Post-mortem analyses of coronary arteries have indicated that obesity (associated with a high accumulation of abdominal fat measured at autopsy) was predictive of earlier and greater extent of large vessels atherosclerosis as well as increase of coronary fatty streaks. Metabolic syndrome linked to abdominal obesity is also predictive of recurrent coronary events both in post-myocardial infarction patients and among coronary artery disease men who underwent a revascularization procedures. It is suggested that until the epidemic progression of obesity is stopped and obesity prevented or at least properly managed, cardiologists will be confronted to an evolving contribution of risk factors where smoking, hypercholesterolemia and hypertension may be relatively less prevalent but at the expense of a much greater contribution of abdominal obesity and related features of the metabolic syndrome.