Adaptive Servo-Ventilation in Cardiac Function and Neurohormonal Status in Patients With Heart Failure and Central Sleep Apnea Nonresponsive to Continuous Positive Airway Pressure
Does effective suppression of central sleep apnea (CSA) by adaptive servo-ventilation (ASV) improve underlying cardiac dysfunction among patients with heart failure (HF) in whom CSA was not effectively suppressed by continuous positive airway pressure (CPAP)?
This is a prospective, single-center, randomized, single-blind trial. Patients were recruited from both cardiology and sleep medicine practices. Seventy-four HF patients with CSA on CPAP were screened. Inclusion criteria were as follows: 1) previous diagnosis of moderate to severe CSA, defined as apnea-hypopnea index (AHI) ≥15 events/hour, of which ≥50% were central events; 2) on CPAP therapy for ≥3 months but current (within 1 month) AHI on CPAP remained ≥15 events/hour with polysomnography; 3) history of persistent systolic HF (even after CPAP initiation), defined as a left ventricular ejection fraction (LVEF) <50% on echocardiography and New York Heart Association class ≥II; and 4) absence of HF exacerbations while receiving stable-dose optimal medical therapy within the previous 3 months. Exclusion criteria were: 1) age <20 or ≥80 years; 2) HF primarily due to organic valvular heart disease, with anatomic alteration of the valve; 3) need for cardiac resynchronization therapy; 4) chronic obstructive pulmonary disease with ventilatory impairment; 5) need for dialysis; and 6) history of stroke with neurological deficit.
A total of 23 men were enrolled: average age 65, three-fourths with nonischemic cardiomyopathy, average EF 32%, and average baseline AHI 47. Twelve were assigned to the ASV-mode group, and 11 were assigned to the CPAP-mode group. Three months after randomization, the ASV mode was significantly more effective in suppressing the AHI (from 25.0 ± 6.9 events/hour to 2.0 ± 1.4 events/hour; p < 0.001) compared to the CPAP mode. Compliance was significantly greater with the ASV mode than with the CPAP mode. Improvement in LVEF was greater with the ASV mode (32.0 ± 7.9% to 37.8 ± 9.1%; p < 0.001) than with the CPAP mode.
Patients with HF and unsuppressed CSA despite receiving CPAP may receive additional benefit by having CPAP replaced with ASV. Additionally, effective suppression of CSA may improve cardiac function in HF patients.
Several mechanisms explaining how CSA suppression by ASV improved cardiac function were discussed in this article. Suppression of sympathetic nerve activity observed by a greater reduction in 24-hour urinary norepinephrine levels in the ASV group compared with the CPAP group could explain the observed fall in LV end-diastolic dimensions, reduction in mitral insufficiency, and increased EF. Long-term effects of CSA treatment by ASV are not known. Randomized and longer-term trials, including mortality outcomes, are warranted.
Keywords: Pulmonary Disease, Chronic Obstructive, Polysomnography, Heart Failure, Cardiovascular Diseases, Single-Blind Method, New York, Sleep Apnea Syndromes, Cardiac Resynchronization Therapy, Echocardiography
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