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 SaO(2) nadir 
(69% vs 77%, p=0.003) than those without arrhythmia. The prevalence of BA in 
patients with AHI>or=30/h was significantly higher than that observed in those 
with AHI<30/h (7.8% vs 1.5%, respectively; chi(2)=5.61, p=0.01). In contrast, 
patients with tachyarrhythmia (TA) had no significant differences in AHI, mean 
desaturation amplitude or SaO(2) 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 beta(2)-treatment may play a role in the 
development of TA during sleep.