Background: Sleep-disordered breathing is a common condition associated with nocturnal hypoxaemia, sympathetic activation and haemodynamic stress that can trigger arrhythmias. We examined whether preoperatively diagnosed disordered breathing was associated with an increased incidence of atrial fibrillation after coronary artery bypass surgery.
Methods: A sleep study was performed in 121 consecutive patients, who were monitored prospectively until discharge from hospital after surgery. Disordered breathing was defined as an apnoea-hypopnoea index (AHI) > or = 5 or an oxygen desaturation index (ODI) > or = 5. All episodes of atrial fibrillation requiring pharmacological intervention or cardioversion were included in the analysis.
Results: Atrial fibrillation was diagnosed in 32% of patient with AHI > or = 5 (25 of 78) and in 18% patients with AHI < 5 (7 of 39, P = 0.11). Similarly, atrial fibrillation was diagnosed in 39% of patients with ODI > or = 5 (19 of 49) and in 18% of patients with ODI < 5 (13 of 72, P = 0.02). In a multiple-logistic regression model including age, left ventricular function, aortic cross clamp time, maximum postoperative level of lactate dehydrogenase and disordered breathing (ODI > or = 5), greater age and disordered breathing were independent predictors of postoperative atrial fibrillation. The relative risk of atrial fibrillation was 2.0 (95% confidence interval 1.1-3.8) for a 10-year increase in age and 2.8 (95% confidence interval 1.2-6.8) for disordered breathing (ODI > or = 5).
Conclusions: Pre-operatively diagnosed sleep-disordered breathing with nocturnal hypoxaemia is an independent predictor of atrial fibrillation after coronary bypass surgery.