Nocturnal cardiac arrhythmia in patients with obstructive sleep apnea

Background and purpose: Nocturnal cardiac arrhythmias occur in patients with obstructive sleep apnea (OSA), reportedly as a consequence of the autonomic effects of recurrent apnea with subsequent oxygen desaturation. We have investigated whether different patterns of OSA are associated with specific arrhythmia during sleep. Patients and methods: Electrocardiographic (ECG) data recorded during polysomnography (PSG) were analysed in 257 consecutive OSA patients to determine the prevalence of cardiac rhythm disturbances, and to relate these to breathing pattern (normal, apnea/hypopnea, recovering ventilation, snoring) and oxygen saturation. Results: Arrhythmias were found in 18.5% of patients. Patients with nocturnal bradyarrhythmia (BA) had higher values of ventilatory disturbance (apnea-hypopnea index [AHI] 58.8 ± 36.8 vs 37.2 ± 30.3, p = 0.02), mean desaturation amplitude (8.9 ± 4 vs 5.9 ± 3.4%, p = 0.03), and a lower SaO₂ nadir (69% vs 77%, p = 0.003) than those without arrhythmia. The prevalence of BA in patients with AHI ≥ 30/h was significantly higher than that observed in those with AHI <30/h (7.8% vs 1.5%, respectively; χ² = 5.61, p = 0.01). In contrast, patients with tachyarrhythmia (TA) had no significant differences in AHI, mean desaturation amplitude or SaO₂ nadir than those without arrhythmia. No associations were found between arrhythmia and the presence of comorbidity or concomitant medical therapy, except for an association between tachyarrhythmia and chronic obstructive pulmonary disease (COPD) (odds ratio 2.53; 95% confidence intervals 1.1-5.8, p = 0.03). Conclusions: We conclude that while BA during sleep is associated with OSA severity, concomitant COPD or β₂-treatment may play a role in the development of TA during sleep.