Obesity and the heart

Abstract

Obesity has been identified as an independent risk factor for coronary heart disease and congestive heart failure. Although congestive heart failure can be secondary to coronary heart disease, in morbid obesity these conditions can be independent. Cardiac structure and function can be altered even in the absence of systemic hypertension and underlying organic heart disease. In obese patients total blood volume increases and creates a high cardiac output state that may cause ventricular dilatation and ultimately eccentric hypertrophy of the left (and possibly the right) ventricle. Eccentric left ventricular hypertrophy produces diastolic dysfunction. Systolic dysfunction may ensue due to excessive wall stress if wall thickening fails to keep pace with dilatation. This disorder is referred to as obesity cardiomyopathy. The frequent coexistence of systemic hypertension in obese individuals facilitates development of left ventricular dilatation and hypertrophy. Congestive heart failure may occur and may be attributable to left ventricular diastolic dysfunction or to combined diastolic and systolic dysfunction. The risk of coronary heart disease seems to be more strictly correlated to central obesity than to increased body mass index. Insulin resistance seems to be the key factor that links obesity and ischaemic heart disease. In such a condition the so called Syndrome X appears. It is characterized by: obesity, systemic hypertension, diabetes mellitus, hypertriglyceridaemia and reduced HDL cholesterol levels. Considering that left ventricular hypertrophy is often present, many risk factors coexist in obese patients. Weight loss is very useful in obese patients. It may reduce mortality and morbidity for coronary heart disease and delay or avoid the appearance of congestive heart failure. It is proved that after weight loss, blood pressure, glucose, cholesterol, triglycerides and left ventricular mass decrease.