N-of-1 Trials for Heart Failure with Preserved Ejection Fraction

Inclusion Criteria: 1. Ambulatory adults age ≥ 65 years with HFpEF, according to ACC/AHA guidelines (signs and symptoms of heart failure AND ejection fraction ≥ 50%) 2. Taking beta-blocker Exclusion Criteria: 1. Alternate cause(s) of HFpEF Syndrome: 1. Severe aortic stenosis 2. Moderate-severe mitral stenosis 3. Constrictive pericarditis 4. High output HF 5. Infiltrative cardiomyopathy 2. Other compelling indication(s) for beta-blocker 1. Prior EF \< 50% 2. Hypertrophic cardiomyopathy 3. Angina 4. Acute coronary syndrome, myocardial infarction, or coronary artery bypass surgery in prior 3 years 5. History of ventricular tachycardia/arrhythmia 6. Atrial arrhythmia with hospitalization for rapid ventricular response, prior 1 year 7. Heart rate \>100 bpm within the prior 3 months 8. Atrial arrhythmia with ventricular rate \>90 per minute in the prior 3 months 9. Systolic blood pressure readings \>160 mmHg within the prior 3 months, unless classified as white coat hypertension/effect (and home blood pressures below 140 mmHg) 10. Non-cardiac indications (e.g., migraine prevention, anxiety symptom management, hyperthyroidism, essential tumor reduction) 3. Clinical instability (N-of-1 trials are appropriate for stable conditions only) 1. Decompensated heart failure 2. Hospitalization in the past 30 days 3. Medication changes or procedures in the prior 14 days that could confound observations/data at PI discretion 4. Anticipated medication changes or procedures in subsequent 3 months that could confound observations/data at PI discretion 5. Clinical instability from other medical issues 4. Estimated life expectancy \< 6 months 5. Moderate-severe dementia or psychiatric disorder precluding informed consent 6. Language barrier that will preclude informed consent and ability to comprehend study procedures 7. Non-compliance or inability to complete study procedures 8. Enrollment in a clinical trial not approved for co-enrollment 9. Any condition that, in the Principal Investigator or treating physician's opinion, makes the patient unsuitable for study participation