Adaptive servo-ventilation to treat central sleep apnea in heart failure with reduced ejection fraction: the Bad Oeynhausen prospective ASV registry

Central sleep apnea (CSA) is highly prevalent in heart failure patients with reduced left ventricular ejection fraction (HF-REF). The Bad Oeynhausen Adaptive Servo-ventilation (ASV) registry (NCT01657188) was designed to investigate whether treatment of CSA with ASV improved survival in HF-REF patients; the effects of ASV on symptoms and cardiopulmonary performance were also investigated. From January 2004 to October 2013, the registry prospectively enrolled HF-REF patients [NYHA class II, left ventricular ejection fraction (LVEF) 45%] with moderate to severe predominant CSA [apnea-hypopnea index (AHI) 15/h]. ASV-treated patients were followed up at 3, 6, 12 and 24 months, including natriuretic peptide concentrations, blood gas analyses, echocardiography, 6-min walk distance (6MWD), and cardiopulmonary exercise (CPX) testing. 550 patients were included [age 67.7 +/- 10 years, 90% male, 52% in NYHA class III, LVEF 29.9 +/- 8%, AHI 35.4 +/- 13.6/h, and time with nocturnal oxygen saturation < 90% (T < 90%) 58 +/- 73 min]; ASV was prescribed to 224 patients. Over a median follow-up of 6.6 years, 109 (48.7%) ASV-treated patients and 191 (58.6%) controls died (adjusted Cox modelling hazard ratio of 0.95, 95% confidence interval 0.68-1.24; p = 0.740); older age, lower LVEF, impaired renal function, low sodium concentration, and nocturnal hypoxemia were significant predictors of mortality. Patient reported NYHA functional class improved in the ASV group, but LVEF, CPX, 6MWD, natriuretic peptides and blood gases remained unchanged. Long-term ASV treatment of predominant CSA in HF-REF patients included in our registry had no statistically significant effect on survival. ASV improved HF symptoms, but had no significant effects on exercise capacity, LVEF, natriuretic peptide concentrations or blood gases during follow-up as compared to control patients.