PrEcision Pacing in HFpEF: the PEP-HFpEF Trial

The PEP-HFpEF study is a prospective, single-center mechanistic study evaluating personalized heart rate pacing (myPACE) in patients with heart failure with preserved ejection fraction (HFpEF) and existing cardiac physiologic pacemakers. Participants will undergo sequential periods of standard and personalized pacing with serial physiologic assessments to evaluate the effects of myPACE on exercise capacity, cardiac function, biomarkers, quality of life, and clinical outcomes.

Inclusion Criteria: * Age ≥18 years. * Diagnosis of heart failure with preserved ejection fraction (HFpEF), defined as left ventricular ejection fraction (LVEF) ≥50% with symptoms and signs consistent with heart failure as determined by the treating investigator. * New York Heart Association (NYHA) Class II or III symptoms despite stable, maximally tolerated guideline-directed medical therapy. * Pre-existing FDA-approved cardiac physiologic pacemaker (e.g., conduction system pacing or cardiac resynchronization therapy) implanted for a standard clinical indication and capable of individualized lower-rate programming. * Expected to require ongoing pacemaker therapy throughout the study period. * Clinically stable at enrollment, without recent major changes in heart failure status that, in the opinion of the investigator, would interfere with interpretation of study outcomes. * Able and willing to provide written informed consent. * Able and willing to comply with all study procedures, including pacemaker programming, cardiopulmonary exercise testing (CPET), echocardiography, blood pressure measurements, autonomic testing, blood collection, and follow-up visits. Exclusion Criteria: * Age \