A Preliminary Study for INFORMED

This is an unblinded NIH Stage I of Behavioral Intervention Development trial, using serial multiple-period single participant crossover design. Investigators will enroll 20 participants, conducting an N-of-1 trial in each. The intervention is a two-arm crossover withdrawal/reversal design (On [A] vs. Off [B]) with up to 6 periods, each period lasting up to 6 weeks. The sequence of treatment will be randomized to either ABAB or BABA. Each participant will have the option to participate in additional (no more than 6) periods if they wish to gather more data. The intervention drug will be beta-blockers, previously prescribed to the participants by their physician. The investigators have developed a titration algorithm, where during the On period (A), participants will be on their baseline beta-blocker dose (or the highest dose they can safely tolerate). During the Off period (B), their beta-blockers will be down-titrated and subsequently discontinued (or at the lowest dose they can safely tolerate); we will decrease the dose of the beta-blocker by 50% every week regardless of which beta-blocker they are on. When returning to On, from Off, we will up-titrate by 50% until reaching their home dose (or the highest dose they can safely tolerate).

Inclusion criteria

• Ambulatory adults age ≥ 65 years with HFpEF, according to ACC/AHA guidelines (signs and symptoms of heart failure AND ejection fraction ≥ 50%)
• Taking beta-blocker

Exclusion criteria

• Alternate cause(s) of HFpEF Syndrome:

• Severe aortic stenosis
• Moderate-severe mitral stenosis
• Constrictive pericarditis
• High output HF
• Infiltrative cardiomyopathy
• Other compelling indication(s) for beta-blocker

• Prior EF < 50%
• Hypertrophic cardiomyopathy
• Angina
• Acute coronary syndrome, myocardial infarction, or coronary artery bypass surgery in prior 3 years
• History of ventricular tachycardia/arrhythmia
• Atrial arrhythmia with hospitalization for rapid ventricular response, prior 1 year
• Heart rate >100 bpm within the prior 3 months
• Atrial arrhythmia with ventricular rate >90 per minute in the prior 3 months
• 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)
• Non-cardiac indications (e.g., migraine prevention, anxiety symptom management, hyperthyroidism, essential tumor reduction)
• Clinical instability (N-of-1 trials are appropriate for stable conditions only)

• Decompensated heart failure
• Hospitalization in the past 30 days
• Medication changes or procedures in the prior 14 days that could confound observations/data at PI discretion
• Anticipated medication changes or procedures in subsequent 3 months that could confound observations/data at PI discretion
• Clinical instability from other medical issues
• Estimated life expectancy < 6 months
• Moderate-severe dementia or psychiatric disorder precluding informed consent
• Language barrier that will preclude informed consent and ability to comprehend study procedures
• Non-compliance or inability to complete study procedures
• Enrollment in a clinical trial not approved for co-enrollment
• Any condition that, in the Principal Investigator or treating physician's opinion, makes the patient unsuitable for study participation