SUBJECTS AND METHODS: The subjects were 197 patients who were referred to the Sleep Research Center of Korea University Medical Center for polysomnography due to snoring and sleep apnea from Jan. 1st 2000 to July 31st 2002. Of the 197 patients, 44 with severe sleep apnea syndrome, whose respiratory disturbance index (RDI) exceeded 40/hr, were enrolled. Their electrograms on polysomnography before and after nCPAP therapy were analyzed.

RESULTS: Of the 44 subjects, 32 (72.8%) showed cardiac arrhythmias. The types of arrhythmias were atrial premature beats (APBs, n=17), premature ventricular complexes (PVCs, n=15), sinus bradycardia (heart rate less than 40 per minute, n=6), sinus pause (n=1), and sinoatrial block (n=5). No fatal arrhythmias were identified. Most, 93.2%, of these arrhythmias arose immediately after hypopneic or apneic episodes, and were accompanied by a significant decrease in SaO2, from 91.4% to 84.7% (p<0.05). After nCPAP therapy, these arrhythmias were completely disappeared in 11 patients (34.4%) and diminished in 15 (46.9%). Hypopneic or apneic episodes were preceded by cardiac arrhythmias in only 36.4% with nCPAP (p<0.05 vs. before).

CONCLUSION: Cardiac arrhythmias were demonstrated in 72.8% of cases of severe sleep apnea syndrome, which were mostly benign and preceded by hypopneic or apneic episodes. nCPAP therapy decreased the frequency of hypopnea and apnea with elevated arterial O2 saturation, and effectively eliminated cardiac arrhythmias.