BACKGROUND: The onset of atrial fibrillation (AFIB) in the postoperative setting has been associated with increased morbidity and mortality in patients undergoing major noncardiothoracic operations. The purpose of this study was to determine the incidence, associated complications, and outcomes of AFIB after open aortic operations. STUDY DESIGN: We studied 211 consecutive patients undergoing elective aortic operations at a single hospital during a recent 6-year period. Postoperatively all patients had continuous ECG monitoring in the ICU for a mean (± SD) of 6 ± 8 days and routine cardiac enzyme determinations. RESULTS: AFIB developed in 22 of the 211 patients (10%), a mean (± SD) of 2 ± 1 days after operation, and it lasted for a mean of 4 ± 6 days after onset. Sixteen patients spontaneously reverted to normal sinus rhythm, 3 required cardioversion (2 chemical, 1 electrical), and 3 continued in AFIB at discharge. Four of the 22 patients suffered additional cardiac complications, including antecedent MI in 3 (14%) and sustained cardiogenic shock requiring electrical cardioversion in 1. By comparison, the incidence of MI in the other 189 patients was 4% (no significant difference [NSD]). There were no deaths in the AFIB patients. Cardiac emboli developed in none of the 22 patients, and all patients had normal sinus rhythm on ECG obtained a mean of 14 ± 10 months after discharge. Comparing the 22 patients with AFIB with the 189 patients without AFIB, there were no differences in the mean duration of ICU stay (6 ± 4 versus 6 ± 8 days), total length of hospital stay (10 ± 5 versus 11 ± 10 days), or hospital mortality (0% versus 0.5%). AFIB patients were older (71 versus 66 years, p = 0.016), but there was no difference in gender or use of β-blockers between the two groups. CONCLUSIONS: These data suggest that AFIB is not uncommon after aortic operations but is not associated with increased morbidity, mortality, or length of hospital stay. Although a minority of affected patients can have other cardiac complications such as MI, these complications are usually recognized before the onset of AFIB. AFIB does not affect the outcomes of aortic operations. Most patients will revert spontaneously to normal sinus rhythm and do not require longterm anticoagulation to prevent thromboembolic complications.