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

Area of Science:

• Cardiology
• Metabolic Research
• Animal Models

Background:

• Obesity is linked to atrial fibrillation (AF), but whether weight loss can reverse obesity-induced atrial changes is unknown.
• Understanding the impact of weight loss on the atrial substrate is crucial for managing AF in obese individuals.

Purpose of the Study:

• To evaluate the effect of weight loss on the atrial substrate in an obese ovine model.
• To determine if weight loss can reverse structural and electrophysiological changes associated with obesity in the atria.

Main Methods:

• Thirty sheep were induced into sustained obesity and randomized to sustained obesity, 15% weight loss, or 30% weight loss groups over 32 weeks.
• Comprehensive assessments included dual-energy x-ray absorptiometry, echocardiogram, cardiac MRI, electrophysiological studies, and histological/molecular analyses of atrial tissue.
• Control group consisted of eight lean sheep.

Main Results:

• Obesity increased left atrial pressure, inflammation, fibrosis, and AF burden, while decreasing connexin 43 expression.
• A 30% weight reduction significantly decreased body fat, left atrial pressure, inflammation, fibrosis, and AF inducibility.
• Weight loss improved atrial electrophysiology, including increased effective refractory period and conduction velocity, and decreased conduction heterogeneity.

Conclusions:

• Weight loss in an obese ovine model induced significant structural and electrophysiological reverse remodeling.
• These findings support a direct role for obesity in the atrial substrate for AF and underscore the potential therapeutic benefit of weight reduction in AF patients.