Indicators of atrial fibrillation risk in cardiac surgery patients on prophylactic amiodarone.

Background: Atrial fibrillation is a common complication of cardiothoracic surgery (coronary artery bypass graft surgery or cardiac valve repair or replacement). Although predictors of postoperative atrial fibrillation have been explored in patients not receiving prophylactic antiarrhythmic therapy, independent predictors of postoperative atrial fibrillation in patients receiving prophylactic amiodarone have not been elucidated.

Methods: This was a substudy of a clinical trial evaluating the efficacy of an amiodarone regimen or an atrial-septal pacing strategy on the occurrence of postoperative atrial fibrillation. The association between the occurrence of postoperative atrial fibrillation and preoperative, intraoperative, and postoperative data from the total study population and the amiodarone and placebo subpopulations were explored using multiple logistic regression analysis.

Results: The following clinical factors were independent predictors of postoperative atrial fibrillation in the total population: age (p < 0.001), history of atrial fibrillation (p = 0.021), diabetes mellitus (p = 0.008), and high-dose postoperative nonsteroidal antiinflammatory drug use (p = 0.038). Age (p = 0.016), history of mitral regurgitation (p = 0.029), heart failure (p = 0.010), and postoperative nonsteroidal antiinflammatory drug use (p = 0.038) were independent predictors when amiodarone was used, and age was the only predictor of postoperative atrial fibrillation (p = 0.024) among patients treated with placebo.

Conclusions: This subanalysis demonstrates some novel predictors of postoperative atrial fibrillation, including diabetes mellitus and postoperative nonsteroidal antiinflammatory drug use. We have also demonstrated that predictors of atrial fibrillation differ when prophylactic amiodarone is used.