1204Pericardial fat volume outperforms classic risk markers in the prediction of relapse after pulmonary vein isolation

Abstract

Abstract Introduction Pericardial adipose tissue has been implicated in the pathophysiology of atrial fibrillation (AF), but its relevance to clinical practice remains uncertain. The aim of this study was to assess the relative importance of pericardial fat as predictor of recurrence after pulmonary vein isolation (PVI). Methods We assessed 453 patients (278 men, age 61±13 years, 348 paroxysmal AF) with symptomatic AF undergoing cardiac CT prior to a PVI procedure. Pericardial fat was quantified on contrast-enhanced images using a new simplified semi-automated method. The study endpoint was symptomatic and/or documented AF recurrence. Results Over a median follow-up of 14 months (IQR 7–23), 170 patients (38%) relapsed. Survival analysis showed significant differences in AF-free survival across tertiles of pericardial fat (Figure). Pericardial fat volume was weakly correlated to body mass index [(BMI), Pearson's R=0.34]. After adjustment for BMI and other univariate predictors of relapse, three variables emerged independently associated with time to AF recurrence: non-paroxysmal AF (HR 2.08, 95% CI: 1.51–2.87, p<0.001), indexed left atrial (LA) volume (HR 1.02 per mL/m2, 95% CI: 1.01–1.02, p<0.001), and indexed pericardial fat volume (HR 1.50 per mL/m2, 95% CI: 1.37–1.64, p<0.001). Based on the Wald test, indexed pericardial fat volume was the strongest of these predictors of relapse (X2 values of 20, 13, and 77, respectively). The population attributable risk (PAF) was higher for pericardial fat (PAF=37% for 1st vs 4th quartile) vs LA volume (PAF=11% for 1st quartile vs 4th quartile) and non-paroxysmal AF (PAF=23%). Pericardial fat volume also showed greater discriminate power than indexed LA volume, with a C-statistic of 0.80 (95% CI 0.76–0.85) vs. 0.61 (95% CI 0.55–0.66), p for difference <0.001. The method for quantifying pericardial fat showed high inter-observer reproducibility (Pearson's R=0.90) and was quick to perform (38±3 seconds). Conclusion Pericardial fat volume is a strong independent predictor of AF relapse after PVI, outperforming classic risk markers such as LA volume and type of AF. The underlying mechanisms of this association deserve further study. Meanwhile, this simple parameter may help select patients who are more likely to derive sustained benefit from AF ablation.