Patients With Heart Failure With Preserved Ejection Fraction Adherence to ASV Therapy (PEP ASV)

Inclusion Criteria: * 1\. Patients 18 years or older 2. Patients with heart failure with preserved ejection fraction (HFpEF; LVEF ≥50%) 3. Hospital admission or equivalent (such as ER visit alone or clinic visit alone) and acute decompensated HF as determined by: 1. Dyspnea at rest or with minimal exertion AND 2. Treatment with at least one dose of IV diuretic or ultrafiltration AND 3. At least two of the following signs and symptoms: i. Orthopnea ii. Pulmonary rales that do not clear with cough iii. Congestion on chest X-ray iv. Local BNP or NT pro-BNP level: * No current AFib: BNP≥100 pg/mL or NT pro-BNP≥300 pg/mL OR * Current AFib: BNP≥150 pg/mL or NT pro-BNP≥450 pg/mL 4. Sleep disordered breathing (SDB) documented by screening polygraphy with an AHI≥15 events/hour (e/hr) 5. Patient is able to fully understand study information and sign informed consent Exclusion Criteria: 1. Right-sided heart failure without left-sided failure 2. Current chronic use (within 4 weeks of registry entry) of any PAP therapy (e.g., CPAP, APAP, or bi-level) or contraindicated for PAP therapy 3. Sustained systolic blood pressure \<80 mmHg at baseline 4. Complex congenital heart disease 5. Constrictive pericarditis 6. Chronic hypoxemia as evidenced by sustained oxygen saturation ≤ 85% at rest during the day or at start of nocturnal oximetry recording or regular use of oxygen therapy (day or night) 7. Transient ischemic attack (TIA) or Stroke within 3 months prior to registry entry 8. Definite clinically evident acute myocardial infarction within 3 months of registry entry 9. Known amyloidosis, hypertrophic obstructive cardiomyopathy, or arteriovenous fistulas 10. Moderate or greater valvular heart disease as the primary reason for heart failure 11. In the opinion of the investigator, the index acute decompensated HF event was not due primarily to uncontrolled AFib with fast ventricular response rate 12. Inability to comply with planned study procedures