Impact of body composition, fat distribution and sustained weight loss on cardiac function in obesity

Obesity is associated with alterations in left ventricular function varying along with the degree of fatness, but the mechanisms underlying this co-variation are not clear. In a case-control study we examined how sustained weight losses affect cardiac function and report on how body composition and fat distribution relate to the left ventricular performance.

At the 10-year follow-up of the Swedish obese subjects (SOS) study cohort we identified 44 patients with sustained weight losses after bariatric surgery (surgery group) and 44 matched obese control patients who remained weight stable (obese group). We also recruited 44 matched normal weight subjects (lean group). Dual-energy X-ray absorptiometry, computed tomography and echocardiography were performed to evaluate body composition, fat distribution and cardiac function.

BMI was 42.5 kg/m(2), 31.5 kg/m(2) and 24.4 kg/m(2) for the obese, surgery and lean groups respectively. Increasing degree of obesity was associated with larger left ventricular volumes (p < 0.001), higher cardiac output (p < 0.001), reduced systolic myocardial velocity (p<0.001) and impaired ventricular relaxation (p = 0.015). In multivariate analyses, left ventricular volume, stroke volume and cardiac output primarily associated with lean body mass, whereas blood pressure, heart rate and variables reflecting cardiac dysfunction were more related to total body fat and visceral adiposity.

Obesity is associated with discrete but distinct disturbances in the left ventricular performance appearing to be related to both the total amount of body fat and degree of visceral adiposity. Patients with sustained weight losses display superior left ventricular systolic and diastolic functions as compared with their obese counterparts remaining weight stable.