Quantification of epicardial adipose tissue in patients undergoing hybrid ablation for atrial fibrillation

Objectives: Epicardial adipose tissue volume (EAT-V) has been linked to atrial fibrillation (AF) recurrences after catheter ablation. We retrospectively studied the association between atrial EAT-V and outcome after hybrid AF ablation (epicardial surgical and endocardial catheter ablation). Methods: On preoperative cardiac computed tomography angiography scans, the left atrium and right atrium were manually delineated using the open source ImageJ. With custom-made automated software, the number of pixels in the regions of interest on each slice was calculated. On the basis of the Hounsfield units, pixel size and slice thickness, EAT-V was computed and normalized in relation to the body surface area (BSA) and the myocardial tissue volume. Results: Eighty-five patients were included. Left atrial and right atrial EAT-V normalized to BSA were not significantly different between paroxysmal and persistent AF [0.84 (0.51-1.50) vs 0.81 (0.57-1.18), 1.74 (1.02-2.56) vs 1.55 (1.26-2.18), all P = 0.9], neither between the acute conduction block and no acute conduction block in the epicardial box lesion [0.92 (0.55-1.39) vs 0.72 (0.55-1.24), P = 0.5, right atrium not applicable], nor between the sinus rhythm and arrhythmia recurrence after 12 months [0.88 (0.55-1.48) vs 0.63 (0.47-1.10), 1.61 (1.11-2.50) vs 1.55 (1.20-2.20), all P > 0.1]. Left atrial EAT-V normalized to myocardial tissue volume was not different between the groups. Conclusions: This study could neither confirm that EAT-V was predictive of recurrence of supraventricular arrhythmias in patients undergoing a hybrid AF ablation, nor that EAT-V was different between patients with paroxysmal AF and persistent and long-standing persistent AF. This suggests that EAT-V might not affect the outcome in surgical ablation procedures and therefore should not influence preoperative or intraoperative decision-making.