This is a prospective interventional study to better understand i) the prevalence of Obstructive Sleep Apnea (OSA) in Heart Failure with preserved Ejection Fraction (HFpEF), ii) its hemodynamic correlates, and iii) the impact of intervention with Continuous Positive Airway Pressure (CPAP) on quality of life.

This is a prospective non-randomized observational study which will recruit patients with gold standard HFpEF defined by exercise catheterization or following HF hospitalization. The prevalence of OSA will be determined in all HFpEF patients at baseline using home sleep apnea testing and all patients will complete the Mayo Sleep Questionnaire. Patients with known OSA at baseline will also be included only for the baseline assessment to accurately estimate prevalence of OSA in gold standard diagnosed HFpEF. The subset of initially recruited patients with HFpEF who have newly diagnosed OSA will be offered and initiated on CPAP therapy to treat their underlying OSA. Repeat evaluation after 3 months of CPAP therapy for end point assessment with remote accelerometry (2 weeks prior to study completion), ESS and KCCQ, which will all be identical to baseline measurements.

Inclusion Criteria:

• Age ≥ 18 years
• Diagnosis of HFpEF by catheterization with resting PCWP>15 mmHg or exercise PCWP>25 mmHg or hospitalization with HFpEF
• Ambulatory (not wheelchair/scooter dependent)
• If no known diagnosis of OSA, must not be pacemaker dependent with either atrial pacing or VVI without sinus rhythm
• If no known diagnosis of OSA, must be able to temporarily hold nitrates or alpha channel blockers for home WatchPAT testing (3 hour washout period)

Exclusion Criteria:

• Ejection fraction <40%
• Obstructive hypertrophic cardiomyopathy
• Constrictive pericarditis or tamponade
• Active myocarditis
• Complex congenital heart disease
• Other valve disease requiring surgical intervention
• Terminal illness (other than HF) with expected survival of less than 1 year
• Inability to comply with planned study procedures
• Pregnancy or breastfeeding mothers

Heart failure patients with preserved ejection fraction.