Heart rate turbulence in patients with obstructive sleep apnea syndrome.

BACKGROUND Heart rate turbulence (HRT) assessment is used as noninvasive method based on physiological sinus node response to the premature ventricular beat. Blunted HRT may indicate the autonomic nervous system impairment and can be helpful in identifying high-risk patients. Obstructive sleep apnea syndrome (OSAS) leads to cardiovascular complications. Autonomic nervous system and baroreflex dysfunctions may play the main role in the development of cardiovascular diseases. In the present study we aimed to assess HRT parameters in OSAS patients with and without coronary artery disease (CAD) in comparison to control group. METHODS HRT analysis (TO--turbulence onset and TS--turbulence slope) was performed in 22 OSAS patients (confirmed by polisomnography, apnea-hypopnea index >or= 15) and 21 healthy persons, obtained from 24-hour ECG recordings. CAD was confirmed in 10 OSAS patients, by positive exercise test ECG and coronary angiography. RESULTS TS was significantly lower in OSAS patients in comparison to control group (1.14 +/- +/- 2.83 vs. 21.28 +/- 16.2, p < 0.001). TO didn't differ in both group. Significant negative correlation between TS and apnea-hypopnea index was observed (r = 0.49, p < 0.01). There were no significant HRT changes in OSAS and CAD patients vs. OSAS without CAD patients, although tendency to more impaired HRT in OSAS and CAD patients was observed. CONCLUSIONS In OSAS patients, blunted HRT (especially TS) was observed. This may indicate baro-reflex dysfunction correlated with the severity of sleep disorders. The additional diagnosis of CAD did not significantly influence HRT parameters.