Obstructive sleep apnoea and nocturnal arrhythmias in patients with ischaemic heart disease

Introduction: Arrhythmias, including atrial fibrillation/flutter (AF), are independent risk factors of mortality in patients with ischemic heart disease (IHD). While there is a growing body of evidence that suggests an association between Obstructive Sleep Apnoea (OSA) and arrhythmias, evidence on this relationship in patients with IHD has been scant and inconsistent. We hypothesize that in patients with IHD, OSA is associated with an increased risk of arrhythmias during sleep. Methods: This is a prospective study of consecutive patients with a previous diagnosis of IHD referred to the sleep laboratory at National University Hospital. Exposed subjects were defined as patients who had an Apnea–hypopnea index (AHI) ≥ 30/hour (OSA). All ECGs were interpreted by the SomteECG analysis software and confirmed by a physician blinded to the presence or absence of exposure. Data was entered using SPSS 15.0 for Windows (SPSS Inc.; Chicago, IL). Arrhythmia subtypes (ventricular, atrial and conduction delay) were analyzed as dichotomous outcomes using multiple logistic regression models. Results: AF (p= 0.003; odds ratio [OR], 13.5; 95% confidence interval [CI], 1.66 – 109.83) was found to be more common in the OSA than the non-OSA group. After adjusting for potential confounders, which included patient characteristics and co-morbidities, compared with those without OSA, IHD patients with OSA had almost a hundred times the odds of experiencing AF during sleep (OR 98.5; 95% CI 2.2 – 4332.9). No significant difference in ventricular and conduction delay arrhythmias was noted between the two groups. Conclusion: We found a significant association between OSA and nocturnal AF in patients with IHD.