After enrollment, baseline data will be collected, and subjects will then have a pacemaker implanted. Subjects will then be randomized 1:1 to either the Atrial Ventricular Node Stimulation (AVNS) therapy or the control group, that will be applied for 24 hours and discontinued at the end of the 24-hour period. Serum biomarkers will be collected and analyzed. After 6 weeks, subjects will be randomized to either the full pacing therapy (TRT + PLR on) or the control group. At 7 months therapy modifications will be made based on initial pacing randomization assignment (full pacing therapy or modified pacing therapy), and a new randomization which applies pacing therapies (either full pacing therapy or modified pacing therapy) to all subjects will be applied. At 10 months all pacing therapy will have a final adjustment and subjects will be evaluated for their final visit at 12-months and exited from the study. Echocardiographic, functional, and health status endpoints will be collected and analyzed to assess therapy efficacy.
FIRE-HFpEF is a multi-center, prospective, randomized, single-blinded, clinical feasibility study. This study will enroll up to 105 subjects with heart failure with preserved ejection fraction in the United States. Data will be collected to evaluate whether pacing therapies can lead to improvements in exercise capacity and health status of subjects.