title: Continuous positive airway pressure increases heart rate variability in heart failure patients with obstructive sleep apnoea.
abstract: Patients with heart failure or OSA (obstructive sleep apnoea) have reduced HF-HRV (high-frequency heart rate variability), indicating reduced cardiac vagal modulation, a marker of poor prognosis. CPAP (continuous positive airway pressure) abolishes OSA in patients with heart failure, but effects on daytime HF-HRV have not been determined. We hypothesized that, in patients with heart failure, treatment of coexisting OSA by CPAP would increase morning HF-HRV. In 19 patients with heart failure (left ventricular ejection fraction <45%) and OSA (>/=20 apnoeas and hypopnoeas/h of sleep), HF-HRV was quantified before and 1 month after randomization to a control or CPAP-treated group. In the control group (n=7), there were no changes in HF-HRV over the 1 month study during wakefulness in the morning. In the CPAP-treated group (n=12) HF-HRV increased significantly during wakefulness in the morning [from 2.43+/-0.55 to 2.82+/-0.50 log(ms(2)/Hz); P=0.002] due to an increase in transfer function between changes in lung volume and changes in HF-HRV (92.37+/-96.03 to 219.07+/-177.14 ms/l; P=0.01). In conclusion, treatment of coexisting OSA by nocturnal CPAP in patients with heart failure increases HF-HRV during morning wakefulness, indicating improved vagal modulation of heart rate. This may contribute to improved prognosis.
authors.affiliation: Sleep and Cardiovascular Physiology Research Laboratories, Mount Sinai Hospital, Toronto, ON, Canada.
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Gilman
authors.forename: John S
authors.initials: JS
authors.lastname: Floras
authors.forename: Kengo
authors.initials: K
authors.lastname: Usui
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Kaneko
authors.forename: Richard S T
authors.initials: RS
authors.lastname: Leung
authors.forename: T Douglas
authors.initials: TD
authors.lastname: Bradley
mesh_terms: D000368:Aged; D000886:Anthropometry; D001016:Aortic Bodies / Q000503:physiopathology; D002940:Circadian Rhythm; D045422:Continuous Positive Airway Pressure; D005260:Female; D006333:Heart Failure / Q000150:complications / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000503:physiopathology / Q000628:therapy*