Abstract 12139: Postoperative Atrial Fibrillation Occurs in Two Distinct Phases After Cardiac Surgery
Purpose: New onset postoperative atrial fibrillation (POAF) is a common complication of cardiac surgery associated with increased morbidity, mortality, and cost of care. However, a time-related risk hazard after surgery has not been described. The objective of this study was to determine the continuous time-related risk (hazard) for new-onset POAF among patients who underwent cardiac surgery for coronary artery disease or valvular pathology.
Methods: Between Jan 2009 and Jan 2012, 1627 patients underwent CABG, valve surgery or both at a single institution. A total of 423 patients experienced POAF without a previous history of atrial fibrillation. The time to first onset of POAF was recorded and a multiphase hazard model was fitted to the data. Multivariate analysis of each phase was also conducted.
Results: Of the 423 who developed POAF, 67 (16%) experienced first-onset during the first 24 hours, 203 (48%) between 24-72 hours, and 153 (36%) at greater than 72 hours. The parametric hazard for POAF is highest immediately after surgery and then decreases for 24 hours (1st phase). It then increases again to a peak at two days and decreases thereafter (2nd phase, see figure). The majority (408, 96%) of POAF occurred within the first seven days. Multivariate analysis of each phase showed risk factors for the 1st phase were older age (p=.01), longer ischemic time (p=.01), and mitral valve procedure (p=.0002). Risk factors for the 2nd phase were older age (p≤.0001), white race (p=.007), increased weight (p≤.0001), and longer ischemic time (p=.05).
Conclusion: In patients undergoing cardiac surgery for coronary disease and/or valve pathology, the hazard for POAF was bimodal, suggesting that the two phases of risk are the result of distinct mechanisms that overlap in time. Further investigation into the mechanisms of POAF with respect to time (1st vs. 2nd phase) is clearly warranted. Subsequent interventions could then be tailored for each phase.
- © 2013 by American Heart Association, Inc.