Implications of continuous positive airway pressure on heart rate variability in patients with obstructive sleep apnea: Does gender matter?

Abstract

Objective:This study was designed to determine the ef-fectiveness of continuous positive airway pressure (CPAP) treatment on the improvement of heart rate variability (HRV) and whether gender plays a role in HRV in patients with mode-rate to severe obstructive sleep apnea syndrome (OSAS).Methods:Consecutive patients with recently diagnosed moderate to severe OSAS underwent continuous synchro-nized electrocardiographic monitoring and were prospec-tively considered for inclusion in the study. HRV was ana-lyzed before starting CPAP therapy and 1 year thereafter. The effects of CPAP on HRV were evaluated in men and women separately to ascertain whether there are gender dif-ferences in the clinical manifestations of OSAS and whether female HRV responses to CPAP are similar to those of men.Results:A total of 18 patients (10 men, median age: 56 years) were included in the study. There were no signifi-cant differences in the baseline clinical characteristics of the male and female patients. After 1 year of CPAP treatment, heart rate decreased (p<0.05) and time domain parameters increased (p<0.05) in both men and women. None of the frequency domain parameters changed in women (p>0.05), whereas the high frequency power measured increased (p<0.05) and the ratio of low frequency to high frequency decreased (p<0.05) in men after 1 year of CPAP treatment. The increase in HRV after 1 year of CPAP therapy was sig-nificantly higher in men than in women (p<0.05).Conclusion:CPAP therapy reduced enhanced cardiac sympathetic nerve activity in patients with OSAS assessed according to HRV. The beneficial effect of long-term CPAP therapy on HRV was more pronounced in men.