Beyond absolute epicardial fat: metabolic disproportionality predicts atrial fibrillation recurrence
F Martins Nunes, L Moura, F Lemos De Sousa, I Rodrigues, A Goncalves, M Almeida, A Lobo, I Neves, M Leite, J Almeida, R Fontes-CarvalhoAbstract
Background
Obesity is a major risk factor for atrial fibrilation (AF), partly through increased epicardial adipose tissue (EAT), which promotes atrial remodeling. Although higher epicardial fat volumes (EFV) correlate with AF burden, their prognostic value after ablation remains uncertain. Emerging data suggest that the metabolic disproportionality of EAT may better reflect arrhythmogenic risk.
Purpose
We aimed to assess whether an epicardial fat/BMI (EF/BMI) index improves prediction of late AF recurrence after ablation.
Methods
We performed a single-center retrospective study of AF patients undergoing catheter ablation (2017–2021) with available EAT measurements. EFV was quantified by cardiac CT, and EF/BMI was calculated as EFV/BMI (kg/m²). Late recurrence was defined as AF beyond a 90-day blanking period. Continuous variables were expressed as mean±SD or median, IQR. Group comparisons used t-test, Mann–Whitney U or chi-square tests. Variables associated with recurrence in univariate analysis entered a multivariable logistic regression model. Discriminative performance was assessed with ROC analysis.
Results
Among 383 patients, 26.3% developed late recurrence. Mean age was 57.4±11.4 years and 64% were male. Recurrence was associated with higher EFV (77 [51–103] vs 72 [49–96] mL; p=0.022) and higher EF/BMI (3.05 [2.2–3.9] vs 2.59 [1.9–3.5]; p=0.021). In univariate analysis, EF/BMI showed a stronger effect (OR=1.26; p=0.006) than EFV (OR=1.008; p=0.006). The EF/BMI ROC curve yielded an AUC of 0.57 (p=0.021). In multivariable analysis, EF/BMI independently predicted recurrence (OR 1.25; p=0.013), second only to AF phenotype (OR 2.61; p<0.001). EFV lost significance when EF/BMI was included, reflecting colinearity.
Discussion
These results highlight the mechanistic role of epicardial adiposity in post-ablation arrhythmogenic vulnerability. Relative fat burden (EF/BMI) provided incremental discriminatory value over absolute EFV, supporting the relevance of metabolic disproportionality in AF substrate remodeling. Although the AUC indicates modest standalone prediction, this aligns with other markers and underscores the potential benefit of integrating EF/BMI into multiparametric clinical models.
Conclusion
The EF/BMI index is a simple, reproducible metric that independently predicts late AF recurrence after catheter ablation. Further studies should validate these findings and define optimized thresholds to refine individualized AF risk stratification.