Abstract Body (Do not enter title and authors here): Background: Body mass index (BMI), a measure of overall obesity, is associated with various cardiovascular conditions including atrial fibrillation (AF). Epicardial adipose tissue (EAT), a visceral type of adipose tissue, distinct from the subcutaneous adipose tissue, promotes AF arrhythmogenesis through proinflammatory properties and proximity to the myocardium. We sought to compare left atrial (LA) EAT volume with BMI, in their relationship to LA structural remodeling (LA volume and fibrosis) and AF recurrence following catheter ablation.
Methods: EAT was assessed via cardiac MRI using the 3D Dixon sequence, and fibrosis was assessed using Late Gadolinium Enhancement (LGE) sequence in 127 AF patients (Panel A). Of this cohort, 101 patients underwent radiofrequency or cryoballoon catheter ablation and were followed for AF recurrence.
Results: The mean age of the cohort was 64±11 years (30.7% female). The mean BMI was 29.7±6.6 kg/m². LA volume index was 57.45±20.58 mL/m², LA EAT index was 18.1±8.5 mL/m², and the LA fibrosis was 18.0±7.9%. Compared to BMI, LA EAT index correlated better with LA volume index (LA EAT: R=0.452, p<0.001; BMI: R=−0.03, p=0.73). Similarly, LA EAT index, compared to BMI, correlated better with LA fibrosis (LA EAT: R=0.387, p<0.001; BMI: R=0.104, p=0.251) (Panel B). The ROC curve for the logistic regression model of LA EAT index in the prediction of AF recurrence had an AUC of 0.77 (95% CI 0.68-0.86, p<0.001) and showed an optimal cutoff value of 14.3 mL/m² to identify patients at risk of AF recurrence post-ablation. Whereas, the ROC curve for BMI in the prediction of AF recurrence post-ablation had an AUC of 0.56 (95% CI 0.44-0.68, p=0.33) (Panel C). Cox regression analysis showed LA EAT (HR = 1.089; 95% CI: [1.049–1.131], p < 0.001) to be an independent predictor of post-ablation AF recurrence.
Conclusion: EAT quantified using cardiac MRI, a reproducible and widely accessible imaging parameter, is a better predictor of LA volume, fibrosis and AF recurrence after catheter ablation than BMI.