Association of Left Atrial Intramyocardial Fat Infiltration With Atrial Arrhythmia Recurrence After Pulsed-Field Ablation for Persistent Atrial Fibrillation

Background Computed tomography (CT)-derived left atrial intramyocardial fat infiltration (inFAT) is an emerging imaging phenotype of the atrial substrate in atrial fibrillation (AF). Objective This study aimed to evaluate inFAT and peri-left atrial epicardial adipose tissue (LA-EAT) using artificial intelligence-based CT analysis software (ADAS 3D) and to assess their association with atrial arrhythmia recurrence after persistent AF ablation. Methods This retrospective single-center study included 59 patients who underwent pulsed-field ablation for persistent AF. inFAT and LA-EAT were quantified using a semi-automated algorithm. Cox regression analysis was performed to evaluate the association of inFAT and LA-EAT with recurrence. Kaplan–Meier analysis was performed after stratification according to the tertile of each parameter. Results During a median follow-up period of 11.2 [6.4–11.9] months, atrial arrhythmia recurrence occurred in 21 (36%) patients. The inFAT volume was significantly greater in patients with recurrence than those without (1.25 [0.78–1.53] vs. 0.72 [0.45–1.09] cm³, *p=* 0.021). In contrast, LA-EAT volume was comparable between the groups (21.8 [13.7–30.4] vs. 17.5 [14.1–26.8] cm³, *p=* 0.419). In Cox regression analysis, higher inFAT was significantly associated with recurrence, whereas LA-EAT was not significantly associated (inFAT: hazard ratio [HR], 1.93; 95% confidence interval [CI], 1.13–3.27; *p=* 0.015; LA-EAT: HR, 1.02; 95% CI, 0.99–1.06; *p=* 0.227). The significant association between inFAT and recurrence remained consistent after adjustment for body mass index. Conclusions Greater inFAT volume was associated with atrial arrhythmia recurrence after pulsed-field ablation for persistent AF, suggesting that inFAT may represent a candidate imaging marker of recurrence risk.