Impact of Epicardial Anterior Fat Pad Retention on Postcardiothoracic Surgery Atrial Fibrillation Incidence

Objectives We conducted a randomized, blinded, controlled study evaluating the impact of anterior fat pad (AFP) maintenance on postoperative atrial fibrillation (POAF) incidence. Background Drugs with antiadrenergic effects reduce POAF. Because the epicardial AFP is parasympathetically innervated, its routine excision during coronary artery bypass grafting (CABG) might precipitate autonomic imbalance and induce POAF. Methods Patients (n = 180, mean age = 66 +/- 10 years, 80% men, 5% with previous atrial fibrillation) undergoing CABG surgery were randomized to either AFP maintenance or AFP removal. Routine prophylaxis against POAF with beta-blockers (85%) and amiodarone (28%) was allowed on the basis of caregivers' discretion. The development of POAF, total hospital costs, and heart rate variability was compared between groups. Results Anterior fat pad maintenance did not reduce POAF incidence (34.8% vs. 35.2%, p = 0.950) or total hospital costs (data as medians with 25%, 75% percentiles: 22,940 dollars [17,629 dollars, 29,274 dollars] vs. 23,866 dollars [18,602 dollars, 30,370 dollars], p = 0.647) but was associated with higher heart rate variability (SD of normal-to-normal RR intervals [SDNN]: 31.7 +/- 24.6 vs. 22.7 +/- 8.3, p = 0.05 and SD of all 5-min mean RR intervals [SDANN 5]: 17.1 +/- 11.9 vs. 10.1 +/- 5.5, p = 0.003) than AFP removal. Conclusions Maintaining the AFP prevents attenuation of parasympathetic tone after CABG but does not reduce POAF or total hospital costs in any appreciable way.