Central Sleep Apnea Prevalence and Impact on Cognitive Function in Patients With Heart Failure With Reduced or Mildly Reduced Left Ventricular Ejection Fraction

Prevalence Phase Inclusion Criteria: 1. Diagnosed with heart failure with reduced or mildly reduced left ventricular ejection fraction (LVEF \<50%) at least 3 months prior to enrollment 2. New York Heart Association (NYHA) functional class II-IV 3. Treated and optimized on heart failure guideline directed medical therapy as indicated for at least 4 weeks, including angiotensin receptor-neprilysin inhibitors (ARNI) (or angiotensin converting enzyme inhibitors (ACEI) or angiotensin receptor blocker (ARB)), aldosterone receptor antagonists, beta-blockers and/or sodium glucose co-transporter 2 (SGLT-2) antagonists 4. Age 50 years or older 5. Signed Institutional Review Board (IRB) or Ethics Committee (EC) approved informed consent 6. In the opinion of the investigator, subject is willing and able to comply with the protocol, including the cognitive function assessment Prevalence Phase Exclusion Criteria: 1. Hospitalized for heart failure-related complications in the last 4 weeks 2. History of SDB and/or prior or ongoing treatment for SDB or tested for SDB within the prior year Cognitive Phase Inclusion Criteria: 1. AHI ≥ 15 events per hour and CAHI ≥ 50% of total AHI (Case group) or AHI \< 5 events per hour (Control group) based on the baseline HSAT 2. Per the patient and investigator, willing and able to postpone CSA treatment until completion of the study assessment visit (Visit 3) Cognitive Phase Exclusion Criteria: 1. Color blindness 2. Currently taking opioids 3. Has taken medications for memory/cognition within the last 3 months (including but not limited to cholinesterase inhibitors and/or glutamate regulators) 4. Cerebrovascular accident (stroke or transient ischemic attack) in the last 12 months 5. Diagnosed with neurological disease including but not limited to history of seizures, meningitis, traumatic brain injury, amyotrophic lateral sclerosis, multiple sclerosis, attention-deficit/hyperactivity disorder (ADHD) or autism.