Nocturnal adaptive servoventilation therapy does not decrease sympathetic drive in patients with systolic heart failure: differing effects of PAP and ASV therapy on sympathovagal balance in patients with CSA with and without heart failure

Background: The SERVE-HF trial has generated the hypothesis that positive airway pressure (PAP) (adaptive servo-ventilation in particular; ASV) therapy does not exert favourable effects on sympathovagal balance (SVB) in patients with systolic heart failure (HF) and central sleep apnoea (CSA). The present study, therefore, investigated the differential impact of PAP and ASV on SVB in patients with and without HF.

Methods: SVB (spectral analysis of heart rate and diastolic blood pressure variability) and haemodynamics were non-invasively evaluated in 37 sleeping patients with ongoing mask based therapy for (pre-described) CSA (17 patients with systolic HF with a left ventricular ejection fraction below 50% and 20 patients in the absence of HF) through a monitor system (TaskForce MonitorTM, CNSystems, Graz) connected to the patient in addition to full attended overnight polysomnography (PSG). The night was split into equal parts with no treatment (NT) and (randomized in order), with positive airway pressure therapy (PAP) and ASV. In depth analysis of SVB and hemodynamics was conducted for 10 minutes of stable Non-Rem II sleep taken from each part of the split night.

Results: In sleeping patients with CSA due to systolic HF neither PAP nor ASV elicited any favourable effect on SVB. In contrast, in CSA patients with normal cardiac function (ICSA) similar pressure levels of PAP, but not ASV, favourably altered SVB: the low frequency component of heart rate variability (reflecting sympathetic drive) decreased significantly under PAP (63 ± 20% with NT vs. 53 ± 6% under PAP, p = 0.03) while the high frequency component of heart rate variability increased (reflecting parasympathetic drive; 38 ± 20% with NT vs. 47 ± 26% under PAP, p = 0.03). Likewise, in ICSA patients the very low frequency component of diastolic blood pressure variability was reduced under PAP therapy (6.7 ± 5.1 vs. 4.4 ± 3.5 mmHg², p < 0.01). Haemodynamic effects were neutral in both groups and under both interventions.

Conclusions: Effects of mask based therapy of (central sleep apnoea) on sympathetic drive at night are highly dependent on the mode of ventilation used and underlying cardiac function. PAP (with lower pressure levels) but not ASV favourably decreases sympathetic drive in patients without systolic HF but not in patients with systolic HF.