Oxygen Versus PAP for Sleep Apnea in Heart Failure

The purpose of this study is to compare three treatment modalities for central, or mixed obstructive and central, sleep apnea in patients with chronic heart failure and reduced ejection fraction. The modalities to be tested are nocturnal supplemental oxygen (NSO) and continuous positive airway pressure (CPAP). The main outcome measures will be left ventricular ejection fraction on echocardiogram and peak oxygen consumption on cardiopulmonary exercise testing.

Chronic heart failure (HF) is a highly prevalent disease, with a lifetime risk of approximately 20%. Sleep apnea is a common co-morbid condition, occurring in approximately half of patients with chronic HF, and often has predominantly central or mixed obstructive and central characteristics. Although it is associated with increased mortality in patients with HF, sleep apnea is usually asymptomatic and patients are therefore often unwilling to accept standard therapy with positive airway pressure. At the outset of this study, there were three treatment modalities currently recommended by the American Academy of Sleep Medicine for the treatment of predominantly central sleep apnea in HF patients: nocturnal supplemental oxygen (NSO), continuous positive airway pressure (CPAP) and adaptive servo-ventilation (ASV). Recently, ASV was found to increase mortality in patients with heart failure with reduced ejection fraction and central sleep apnea. There are only limited data on the comparative efficacy and tolerability of these three modalities. The present study is designed to compare these modalities with respect to effects on ventricular function, exercise capacity, and other measures of cardiovascular risk.

Eligibility Criteria:
Inclusion Criteria:

* Veteran receiving care within the Veterans Health Administration healthcare system
* Age 18 years
* Physician diagnosis of chronic heart failure, American Heart Association Stage C-D
* LVEF \<45%
* No change in active cardiac medications for 4 weeks prior to randomization
* Ability to provide informed consent
* Moderate to severe central or mixed central and obstructive sleep apnea, defined as an apnea-hypopnea index (AHI) 15 events per hour, with a central AHI \>5 events/hour

Exclusion Criteria:

* Hospitalization for acute decompensated HF within previous 30 days
* Hospitalization for myocardial infarction or cardiac surgery within previous 90 days
* Presence of a left ventricular assist device
* History of heart transplantation
* Poorly controlled hypertension (\>170/\>110)
* Poorly controlled diabetes (HbA1c \> 9.0)
* Severe renal failure with estimated glomerular filtration rate \<30 ml/min
* Prior stroke with functional impairment or other severe, uncontrolled medical problems that may impair ability to participate in the study exams, based on medical history and review of medical records
* Severe chronic insomnia, with reported usual sleep duration \<4 hours
* Severe daytime sleepiness, defined as Epworth Sleepiness Scale score 18 or higher or a report of falling asleep driving during the previous year, and deemed a safety risk by study physician
* Awake resting oxyhemoglobin saturation \<89%
* Pregnancy
* Smoking by subject or other person in the subject's bedroom, or other open flame in bedroom
* Current use of a positive airway pressure device (including continuous or bi-level positive airway pressure or adaptive servo-ventilation) or supplemental oxygen therapy