Obesity and atrial fibrillation: electroanatomical left atrial remodelling with pronounced changes adjacent to epicardial fat

Background: Obesity is associated with increased risk of atrial fibrillation (AF). The aim of the study was to delineate electrophysiological remodelling and impact of epicardial fat depots on adjacent atrial tissue with obesity. Methods: 112 patients with paroxysmal/persistent AF undergoing AF ablation were screened. After exclusion, 30 patients were enrolled and divided into Obese (BMI≥27) and Control (BMI<27) groups. They underwent cardiac magnetic resonance (CMR) imaging and electro-anatomic mapping of left atrium (LA) prior toAF ablation.Atrial (total and left) and ventricular epicardial fat tissue (EAT)wasdetermined.Global and regional voltage, conduction velocity (CV), fractionation, voltage and CV heterogeneity were determined. Result: The BMI of the obese and control groups was 30.2±2.6 and 25.2±1.3 respectively (p<0.001). Obesity was associated with increase in all measures of EAT (p<0.05). Epicardial fat was distributed adjacent to POS/INF LA. Obesity was associated with reduced global CV (0.86±0.31m/s vs 1.26±0.29; p<0.001) with non-significant increase in conduction heterogeneity (p=0.10) and increased fractionation (54±17% vs 25±10%; p<0.001). Obesity was associated with regional alteration in voltage (p<0.001)with reducedPOSand preserved overall LA voltage, increased low voltage areas (3.4%vs13.9%; p<0.001) predominantly distributed in POS/ INF LA and greater voltage heterogeneity (p=0.001) compared to controls. Amongst various measures of obesity, LA EAT volume correlated best with POS LA CV (p=0.01 vs BMI 0.05). Conclusion: Obesity was associated with marked electroanatomical remodelling of the atria. The remodelling is more pronounced in regions adjacent to epicardial fat depots.