Atrial Fibrillation and Obesity: Reverse Remodeling of Atrial Substrate With Weight Reduction.

Abstract Objectives This study sought to evaluate the effect of weight loss on the atrial substrate for atrial fibrillation (AF). Background Whether weight loss can reverse the atrial substrate of obesity is not known. Methods Thirty sheep had sustained obesity induced by ad libitum calorie-dense diet over 72 weeks. Animals were randomized to 3 groups: sustained obesity and 15% and 30% weight loss. The animals randomized to weight loss underwent weight reduction by reducing the quantity of hay over 32 weeks. Eight lean animals served as controls. All were subjected to the following: dual-energy x-ray absorptiometry, echocardiogram, cardiac magnetic resonance, electrophysiological study, and histological and molecular analyses (fatty infiltration, fibrosis, transforming growth factor β1, and connexin 43). Results Sustained obesity was associated with increased left atrium (LA) pressure (p  Conclusions Weight loss in an obese ovine model is associated with structural and electrophysiological reverse remodeling and a reduced propensity for AF. This provides evidence for the direct role of obesity in AF substrate and the role of weight reduction in patients with AF.