When Sleep and Rhythm Collide: Amiodarone, Obstructive Sleep Apnoea, and Sinus Rhythm Maintenance After Cardioversion

Background: Recurrence of atrial fibrillation (AF) and atrial flutter (AFL) after direct current cardioversion (DCCV) remains a common problem. Several predictors of recurrence have been identified in observational studies. Current guidelines recommend considering amiodarone as an adjunct in patients at high risk of AF/AFL recurrence. However, data in the available literature on the effectiveness of amiodarone in restoring and maintaining sinus rhythm (SR) are sparse. Methods: This observational cross-sectional study analysed retrospective data from 193 patients who underwent elective DCCV for AF/AFL at a single UK cardiac centre, with follow-up at 6 weeks and 12 months. Baseline patient characteristics, including demographic data, echocardiographic findings, co-morbidities, and SR maintenance rate, were compared between patients treated with amiodarone and those without. Multivariate logistic regression was performed to identify parameters associated with DCCV failure. Results: A total of 13.0% of the study population were started on amiodarone before DCCV. Those on amiodarone were more likely to have had a previous failed DCCV (60.0% vs. 21.4%; p < 0.001), AF/AFL duration of at least 12 months (84.0% vs. 53.0%; p = 0.003), a left ventricular ejection fraction (LVEF) of less than 40% (32.0% vs. 14.3%; p = 0.03), and a diagnosis of coronary artery disease (CAD) (32.0% vs. 13.7%; p = 0.02). Treatment with amiodarone was not associated with an increased rate of SR restoration at the time of DCCV (96.0% vs. 92.3%; p = 0.50). However, amiodarone treatment was associated with SR maintenance at 6 weeks (92.0% vs. 54.8%; p < 0.001) and at 12 months (60.0% vs. 26.8%; p < 0.001). Multivariate logistic regression analysis identified obstructive sleep apnoea (OSA) as the only parameter associated with DCCV failure (adjusted odds ratio (OR) 10.5; 95% confidence interval (CI) 2.5–53.5; p = 0.005). There was an increased risk of peri-procedural bradyarrhythmia with amiodarone therapy (adjusted OR 8.85; 95% CI 1.84–42.7; p = 0.007). Conclusions: Amiodarone treatment is associated with maintenance of SR following elective DCCV for AF/AFL. This effect is observed even in patients with risk factors for recurrence, including previous failed DCCV, longer AF/AFL duration, and reduced LVEF. OSA is an independent predictor of DCCV failure; further research is required to delineate the role of early adjunctive amiodarone therapy in these patients.