Impact of amiodarone on the ability of anterior fat pad retention to prevent postcoronary arterial bypass grafting atrial fibrillation incidence: a substudy of the AFIST III (Atrial Fibrillation Suppression Trial III)

BACKGROUND: In the AFIST III (Atrial Fibrillation Suppressions Trial III), anterior fat pad (AFP) retention did not decrease the incidence of postoperative atrial fibrillation (POAF), but prophylaxis with amiodarone did. In order to examine the inter-relationship between amiodarone with AFP retention on POAF, we performed a planned subgroup analysis of AFIST III. METHODS: Coronary artery bypass graft (CABG) patients were randomized to AFP maintenance or removal with prophylactic amiodarone used via the discretion of the caregiver. Patients were categorized into four groups: AFP retention alone, AFP retention plus amiodarone, AFP removal alone and AFP removal plus amiodarone. Multivariate logistic regression was used to calculate adjusted odds ratios with 95% confidence intervals for development of POAF. RESULTS: Amiodarone was used in 28% of the 178 patients (mean age = 66 +/- 10, 80% male, 5% previous atrial fibrillation) undergoing CABG surgery. The overall POAF occurrence rate, regardless of subgroup designation was 35.4%. On multivariate logistic regression, amiodarone plus AFP retention was associated with an 81% reduction in the odds of the patient developing POAF (p = 0.015). Amiodarone prophylaxis without AFP retention was associated with a 68% reduction (p = 0.040). CONCLUSION: Amiodarone prophylaxis with or without AFP retention is an independent negative predictor of POAF. Combining amiodarone with AFP retention may provide a synergistic effect in the prevention of POAF. Further studies are needed to validate the results of this study.