Postoperative atrial fibrillation in patients undergoing aortocoronary bypass surgery carries an eightfold risk of future atrial fibrillation and a doubled cardiovascular mortality.

OBJECTIVE This article presents a study of postoperative atrial fibrillation (AF) and its long-term effects on mortality and heart rhythm. METHODS The study cohort consisted of 571 patients with no history of AF who underwent primary aortocoronary bypass surgery from 1999 to 2000. Postoperative AF occurred in 165/571 patients (28.9%). After a median follow-up of 6 years, questionnaires were obtained from 91.6% of surviving patients and an electrocardiogram (ECG) from 88.6% of all patients. Data from hospitalisations due to arrhythmia or stroke during follow-up were analysed. The causes of death were obtained for deceased patients. RESULTS In postoperative AF patients, 25.4% had atrial fibrillation at follow-up compared with 3.6% of patients with no AF at surgery (p<0.001). An episode of postoperative AF was the strongest independent risk factor for development of late AF, with an adjusted risk ratio of 8.31 (95% confidence interval (CI) 4.20-16.43). Mortality was 29.7% (49 deaths/165 patients) in the AF group and 14.8% (60 deaths/406 patients) in the non-AF group (p<0.001). Death due to cerebral ischaemia was more common in the postoperative AF group (4.2% vs 0.2%, p<0.001), as was death due to myocardial infarction (6.7% vs 3.0%, p=0.041). Postoperative AF was an age-independent risk factor for late mortality, with an adjusted hazard ratio of 1.57 (95% CI 1.05-2.34). CONCLUSIONS Postoperative AF patients have an eightfold increased risk of developing AF in the future, and a doubled long-term cardiovascular mortality.