Automatic positive airway pressure for treatment of obstructive sleep apnea in heart failure Design, rationale, and insights from the APAP randomized controlled trial

Moderate-to-severe obstructive sleep apnea (OSA) has been documented in about 20% of patients with heart failure and reduced ejection fraction (HF-REF). Continuous positive airway pressure (CPAP) is the gold standard for OSA treatment, but very few studies have investigated the effects of CPAP on quality of life, cardiac function, and outcome in HF-REF patients. The Automatic Positive Airway Pressure (APAP) trial is investigating the effects of automatically-adjusting CPAP on cardiopulmonary exercise capacity, OSA parameters, HF status, and quality of life in HF-REF patients with moderate-to-severe OSA. This prospective, single-center trial (DRKS00000446) randomized HF-REF patients (NYHA ae II, ejection fraction ae45%) with moderate-to-severe OSA (apnea-hypopnea index ae15/h) to 6 months of treatment with APAP (AutoSet (TM), ResMed) or nasal strips (control). The primary endpoint is change in cardiopulmonary exercise (CPX) capacity parameters in HF-REF patients treated with nasal strips (control group) or APAP from baseline to 6 months. These parameters include peak oxygen uptake (VO2 peak), predicted peak oxygen uptake (predicted VO2 peak), and oxygen uptake at the individual aerobic-anaerobic threshold (VO2-AT) during a standardized testing protocol. Secondary endpoints include changes in sleep apnea parameters, quality of life, sleepiness, laboratory (including natriuretic peptides) and echocardiographic (ejection fraction, dimensions) measurements, and 6aEuromin walk distance. The APAP trial was designed to assess the efficacy of APAP therapy for OSA on cardiopulmonary exercise capacity in HF-REF patients after 6 months. Secondary endpoints will reveal its effects on quality of life, sleepiness, and metrics of cardiac morphology and function.