Could a sleep apnea machine boost heart efficiency? new study investigates

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

This study (AMEND) is a single centre substudy of the ADVENT-HF trial (NCT01128816). ADVENT-HF is a RCT that will test the effects of ASV on morbidity and mortality in patients with HF and OSA or CSA. The AMEND substudy is a clinical physiologic proposal designed to determine the effects of long-term (6 months) ASV on cardiac energetics and SN function in patients with chronic stable HF and sleep apnea extending our previous evaluation of short-term CPAP in patients with OSA and HF Inclusion Criteria: 1. American Heart Association (AHA) Stages B, C and D heart failure due to ischemic, idiopathic or hypertensive causes with; 2. systolic dysfunction, ejection fraction (EF) ≤45% by echocardiography 3. optimal medical therapy conforming to the AHA guidelines (and for this proposal, stable therapy for \>4 weeks) 4. sleep apnea with an Apnea/hypopnea Index ≥15, which will be divided into OSA (\> 50% events obstructive), or CSA (\> 50% of events central in nature)for patients with OSA, an Epworth Sleepiness Scale score of \>10 and no or mild daytime sleepiness (by the International Classification of Sleep Disorders 5. age \>18 years; 6. willingness to receive ASV therapy 7. informed consent Exclusion Criteria: 1. Myocardial infarction, cardiac surgery or angioplasty within 3 months prior to enrollment, 2. listed for heart transplantation, 3. HF due to primary valvular heart disease, 4. pregnancy 5. current use of ASV or CPAP. 6. awaiting revascularization; 7. previous cardiac transplant; 8. life expectancy less than 6 months due to other co-morbidity; 9. a large transmural scar defined on previous perfusion imaging (severe resting perfusion defect (\<50% uptake) occupying \>25% of the LV); 10. concomitant treatment or use of: tricyclic antidepressants, cocaine or drugs which may alter catecholamine uptake. For heart rate variability (HRV) analysis additional exclusions will include: a) a permanent pacemaker; b) atrial fibrillation; c) significant ventricular arrhythmia or sinus node dysfunction; patients may be excluded from HRV analysis and still be eligible for the sub-study