Endovascular Ablation of the Right Greater Splanchnic Nerve in Subjects Having HFpEF

Up to 150 people will take part in this clinical study. Phase I of the REBALANCE-HF Study The first part of the study took place between January 2021 and March 2023. During this phase, 116 patients participated. Researchers reviewed the results to learn whether the procedure appeared safe and whether it might help improve symptoms in people with heart failure with preserved ejection fraction (HFpEF). This early review showed encouraging results in some patients. It also helped researchers identify a group of patients who seemed more likely to benefit from the procedure. Phase II of the REBALANCE-HF Study: The current phase of the study focuses on patients who have similar characteristics to those who responded well in Phase I. The goal is to confirm whether this group of patients may benefit most from the treatment and whether the procedure should be studied further in a larger future trial. This study will take place at multiple hospitals and research centers. Participants who qualify for the study will be randomly assigned to one of two groups: * Treatment group: The procedure is performed using the Satera Ablation System to treat a nerve called the greater splanchnic nerve. * Control (sham) group: A simulated procedure is performed, but the treatment itself is not delivered. Participants will be assigned to a group by chance, similar to flipping a coin, although twice as many patients will receive the treatment as the sham procedure (2:1 ratio). The group assignment will happen during the procedure after anesthesia is given, and only after the doctor confirms that the patient's anatomy is suitable for the procedure. Blinding: To make sure the results are fair and unbiased: * Participants and their heart failure doctors will not know whether the patient received the treatment or the sham procedure. * The doctor performing the procedure and certain study staff will know which procedure is performed so they can carry out the procedure safely. * The study safety team will also know this information to help monitor patient safety. Sham Procedure: A sham procedure is used to help researchers understand whether any improvements are due to the treatment itself or to the placebo effect. During the sham procedure: A small needle puncture is made in the groin or neck, similar to what is done for many heart procedures. Doctors check the veins to confirm whether the procedure could have been performed. However, the treatment catheter is not used and the nerve is not treated. The sham procedure takes about 45 minutes, which is about the same amount of time as the treatment procedure. Number of Participants: 90 patients were assigned to treatment or sham during Phase I. In Phase II, up to 60 additional patients will be enrolled. About 40 patients will receive the treatment, and about 20 will receive the sham procedure.