Abstract 1563: Weight Loss Improves Right Atrial and Ventricular Function and Metabolism in Obese Humans
Obesity is a major risk factor for right- and left-sided heart failure and atrial fibrillation. Weight loss improves obesity-related left ventricular metabolism and function and left atrial size abnormalities, which may contribute to eventual left-sided heart failure and atrial fibrillation. However, the effect of weight loss on right atrial (RA) and ventricular (RV) function and metabolism is not well-understood. This study investigated whether weight loss also improves RA and RV function and resting RV oxygen requirements. We studied 30 obese (body mass index >30 kg/m2) individuals (73% women) without heart failure before and after weight loss. No subject had ventricular systolic dysfunction or untreated sleep apnea. Subjects underwent either gastric bypass surgery (10 women) or a physician-supervised diet. Two-dimensional echocardiography with tissue Doppler imaging and positron emission tomography (PET) imaging were performed before and after weight loss. RV oxygen consumption was evaluated by 30 minutes of dynamic PET imaging after a bolus injection of 1-11C-acetate. (See Table⇓, mean±SD). Subjects lost an average of 17% of their body weight at a mean of 11 months. RA volumes at each phase in the cardiac cycle, and RV oxygen requirements decreased significantly after weight loss and RV diastolic function (Em) was improved. RV systolic function (Sm) was unchanged. Weight-loss induced change in RV oxygen requirements directly correlated with change in body mass index (r=0.52, p=0.003). Weight loss has major salutary effects on the metabolism, structure, and function of the right heart. Large, interventional trials with long-term follow-up are now needed to determine if these beneficial changes on the heart result in a decreased risk of right-sided heart failure and atrial fibrillation.