Long-term Impact of Continuous Positive Airway Pressure Therapy on Arrhythmia and Heart Rate Variability in Patients With Sleep Apnea.

INTRODUCTION Autonomic dysfunction can alter heart rate variability and increase the incidence of arrhythmia. We analyzed the impact of continuous positive airway pressure (CPAP) on this pathophysiological phenomenon in patients with severe sleep apnea-hypopnea syndrome. METHODS Consecutive patients with recently diagnosed severe sleep apnea-hypopnea syndrome were prospectively considered for inclusion. Incidence of arrhythmia and heart rate variability (recorded on a 24-hour Holter monitoring device) were analyzed before starting CPAP therapy and 1 year thereafter. RESULTS A total of 26 patients were included in the study. CPAP was administered for 6.6 ± 1.8 hours during Holter monitoring. After starting CPAP, we observed a marginally significant reduction in mean HR (80 ± 9 to 77 ± 11 bpm, p=.05). CPAP was associated with partial modulation (only during waking hours) of r-MSSD (p=.047) and HF (p=.025) parasympathetic parameters and LF (p=.049) sympathetic modulation parameters. None of these parameters returned completely to normal levels (p<.001). The number of unsustained episodes of atrial tachycardia diminished (p=.024), but no clear effect on other arrhythmias was observed. CONCLUSIONS CPAP therapy only partially improves heart rate variability, and exclusively during waking hours, and reduces incidence of atrial tachycardia, both of which can influence cardiovascular morbidity and mortality in sleep apnea-hypopnea syndrome patients.