Epicardial adipose tissue (EAT) has been associated with atrial fibrillation (AF), but its role in distinguishing AF subtypes among patients with reduced ejection fraction heart failure (HF) remains uncertain. In a retrospective study published in Frontiers in Cardiovascular Medicine, cardiac computed tomography (CT) was used to quantify EAT volume in 224 patients with AF between 2018 and 2023. 

Patients were classified into combined AF and HF (CAH; left ventricular ejection fraction [LVEF] <50%, n=90) or AF without HF (LVEF ≥50%, n=134). Overall EAT volume was similar between groups (152.3 ± 61.6 vs 166.8 ± 73.2 mL; P=0.12). Across the full cohort, persistent AF (PsAF) was associated with larger EAT volume than paroxysmal AF (PaAF) (166.9 ± 71.0 vs 145.1 ± 61.0 mL; P=0.04).

This difference was confined to the CAH subgroup, where PsAF had higher EAT volume than PaAF (160.2 ± 59.5 vs 127.8 ± 13.4 mL; P=0.03). No such difference was observed in AF patients without HF. EAT correlated with left atrial diameter (r=0.35; P<0.05).

For identifying PsAF, EAT showed limited discrimination overall (AUC=0.60; sensitivity 97.8%; specificity 1.6%) and modestly improved performance in the CAH subgroup (AUC=0.66; sensitivity 86.8%; specificity 45.5%). In that subgroup, left atrial diameter was not significant (AUC=0.58; P=0.28).

These findings suggest higher EAT volume may help identify persistent AF phenotype in patients with reduced ejection fraction HF.