Prevalence of ventricular late potentials in patients with obstructive sleep apnea syndrome

BACKGROUND: It is known from various cardiac disorders that the presence of ventricular late potentials (VLP) in the signal-averaged electrocardiogram (ECG) is associated with an increased risk of sudden cardiac death. HYPOTHESIS: In view of the increased cardiovascular mortality of patients with obstructive sleep apnea syndrome (OSAS), we assessed the prevalence of VLP in these patients. METHODS: In all, 118 consecutive patients with polysomnographically verified OSAS were prospectively studied; 21 snorers without evidence of a sleep-related breathing disorder served as a control group. Signal-averaged ECG and 24-h Holter ECG were performed in all patients and controls, and left ventricular function was determined by radionuclide ventriculography in the OSAS group. Furthermore, patients and controls were followed for up to 45.5 months for arrhythmic events, syncopes, or sudden cardiac death. RESULTS: An abnormal signal-averaged ECG was seen in seven patients (5.9%) and in one snorer (4.8%). Patients with and without VLP did not differ with respect to age, body mass index, left ventricular ejection fraction, or ectopic activity in the 24-h Holter ECG, but the former had significantly higher mean (standard deviation) apnea/hypopnea indices [55.4 (25.2)/h vs. 37.4 (22.6)/h; p < 0.05]. Of the 118 patients, 110 could be followed for 26.7 (7.9) months. During this period, two patients had syncopes and one patient had sudden cardiac death. The seven patients with VLP remained free of events during the follow-up period, as did the 21 snorers. CONCLUSIONS: Patients with OSAS have a low prevalence of VLP in the signal-averaged ECG, not exceeding that in normal subjects. Moreover, abnormal signal-averaged ECGs do not appear to be useful as a prognostic marker.