Accelerated Pacing and Cardiac Filling Pressures During Exercise in Patients With Heart Failure With Preserved Ejection Fraction

Overview

Heart failure with preserved ejection fraction (HFpEF) is a condition where the heart pumps strongly enough, but has trouble relaxing and filling with blood properly. This causes the pressure on the left side of the heart to rise, especially during activity, which can lead to symptoms like shortness of breath and fatigue. Even light activities such as walking or climbing stairs can be difficult, limiting daily life. Recent research suggests that increasing the heart rate in people with HFpEF may help lower this elevated pressure in the heart. Because patients usually experience their symptoms during exercise, this study aims to see whether, during light activity, increasing the heart rate in patients who already have a pacemaker by adjusting its settings, can reduce this elevated pressure in the heart. Furthermore, we will look at how increasing the heart rate affects the amount of blood the heart pumps each minute, another key factor in a person's ability to perform physical activity. The investigators will examine 20 patients using a heart catheter to measure pressures, along with breathing analyses. During the measurements, all patients will perform light-intensity cycling. If increasing the pacemaker rate lowers the pressure in the heart, this simple, non-drug-based intervention could improve daily functioning and comfort for thousands of patients with heart failure, justifying further long-term studies to evaluate effects beyond the immediate changes in heart pressures.

The first phase of the study is the screening phase. During this phase, the investigators will review all patients from the LBBA pacing registries at UZ Leuven and Jessa Hospital to identify who may be eligible. From this review, the investigators will create a list of potential candidates, who will then be contacted during their regular check-up visits, which take place at least once a year. If a patient is found to be eligible during this visit, the study visit will be scheduled within three weeks. If the patient remains eligible, the study tests will begin. A small tube (catheter) will be placed in a vein in the neck and in an artery in the wrist to measure heart pressures and blood oxygen levels. The patient will then be positioned on a slightly reclined stationary bike. During the test, the heart rate will be gradually increased in three steps by adapting the pacemaker settings, and at each step, the pressures inside the heart will be measured. In a final step, the heart rate will return to the level associated with the lowest heart pressure, and blood oxygen levels will be checked. This allows the research team to calculate how much oxygen the heart pumps per minute. After the exercise, the patient will rest briefly while the catheters are safely removed. The entire study visit lasts about three hours, after which participation ends. The full study is expected to be completed once 20 patients have finished all study tests, which should take approximately one year.