Various cardiac arrhythmias frequently occur in patients with sleep apnea, but 
complex analysis of the relationship between their severity and the probable 
arrhythmogenic risk factors is conflicting. The question is what cardiovascular 
risk factors and how strongly they are associated with the severity of cardiac 
arrhythmias in sleep apnea. Adult males (33 with and 16 without sleep apnea), 
matched for cardiovascular co-morbidity were studied by polysomnography with 
simultaneous ECG monitoring. Arrhythmia severity was evaluated for each subject 
by a special 7-degree scoring system. Laboratory, clinical, echocardiographic, 
carotid ultrasonographic, ambulatory blood pressure, and baroreflex sensitivity 
values were also assessed. Moderate sleep apnea patients had benign, but more 
exaggerated cardiac arrhythmias than control subjects (2.53 ± 2.49 vs. 1.13 ± 
1.64 degrees of cumulative severity, p < 0.05). We confirmed strong correlations 
between the arrhythmia severity and known arrhythmogenic risk factors (left 
ventricular ejection fraction and dimensions, right ventricular diameter, 
baroreflex sensitivity, carotid intima-media thickness, age, previous myocardial 
infarction, and also apnea-hypopnea index). In multivariate modelling only the 
apnea-hypopnea index indicating the sleep apnea intensity remained highly 
significantly correlated with the cumulative arrhythmia severity (beta = 0.548, 
p < 0.005). In conclusion, sleep apnea modifying cardiovascular risk factors and 
structures or functions provoked various nocturnal arrhythmias. The proposed 
scoring system allowed a complex analysis of the contribution of various 
triggers to arrhythmogenesis and confirmed the apnea-hypopnea index as an 
independent risk for nocturnal cardiac arrhythmia severity in sleep apnea.