Objective: Splanchnic vasoconstriction augments transfer of blood volume from the abdomen into the thorax, which may increase filling pressures and hemodynamic congestion in patients with noncompliant hearts. Therapeutic interruption of splanchnic nerve activity holds promise to reduce hemodynamic congestion in patients with heart failure with preserved ejection fraction (HFpEF). Here we describe (1) the rationale and design of the first sham-controlled, randomized clinical trial of splanchnic nerve ablation for HFpEF and (2) the 12-month results of the lead-in (open-label) trial's participants., Methods: REBALANCE-HF is a prospective, multicenter, randomized, double-blinded, sham-controlled clinical trial of endovascular, transcatheter, right-sided greater splanchnic nerve ablation for volume management (SAVM) in patients with HFpEF. The primary objectives are to evaluate the safety and efficacy of SAVM and identify responder characteristics to inform future studies. The trial consists of an open-label lead-in phase followed by the randomized, sham-controlled phase. The primary efficacy endpoint is the reduction in pulmonary capillary wedge pressure (PCWP) at 1-month follow-up compared to baseline during passive leg raise and 20W exercise. Secondary and exploratory endpoints include health status (Kansas City Cardiomyopathy Questionnaire), 6-minute walk test distance, New York Heart Association class, and NTproBNP levels at 3, 6 and 12 months. The primary safety endpoint is device- or procedure-related serious adverse events at the 1-month follow-up., Results: The lead-in phase of the study, which enrolled 26 patients with HFpEF who underwent SAVM, demonstrated favorable safety outcomes and reduction in exercise PCWP at 1 month post-procedure and improvements in all secondary endpoints at 6 and 12 months of follow-up. The randomized phase of the trial (n = 44 SAVM; n = 46 sham) has completed enrollment, and follow-up is ongoing., Conclusion: REBALANCE-HF is the first sham-controlled randomized clinical trial of greater splanchnic nerve ablation in HFpEF. Initial 12-month open-label results are promising, and the results of the randomized portion of the trial will inform the design of a future pivotal clinical trial. SAVM may offer a promising therapeutic option for patients with HFpEF., Trial Registration: NCT04592445., Competing Interests: DISCLOSURES MF was supported by the NIH (1OT2HL156812-01) and Doris Duke, and he consults for or owns equity in Abbott, Ajax, Alio Health, Alleviant, Artha, Audicor, AxonTherapies, Bayer, Bodyguide, Bodyport, Boston Scientific, Broadview, Cadence, Cardioflow, Cardionomics, Coridea, CVRx, Daxor, Deerfield Catalyst, Edwards LifeSciences, Echosens, EKO, Feldschuh Foundation, Fire1, FutureCardia, Galvani, Gradient, Hatteras, HemodynamiQ, Impulse Dynamics, Intershunt, Medtronic, Merck, NIMedical, NovoNordisk, NucleusRx, NXT Biomedical, Orchestra, Pharmacosmos, PreHealth, Presidio, Procyreon, ReCor, Rockley, SCPharma, Shifamed, Splendo, Summacor, SyMap, Verily, Vironix, Viscardia, Zoll. SL reports research support from Axon, Corvia, V Wave, Astra Zeneca, Eli Lilly, and Rivus and has consulting relationships with Axon, Corvia, Eli Lilly, and Rivus. BAB receives research support from the National Institutes of Health and the United States Department of Defense as well as research grant funding from AstraZeneca, Axon, GlaxoSmithKline, Medtronic, Mesoblast, Novo Nordisk, and Tenax Therapeutics and has served as a consultant for Actelion, Amgen, Aria, BD, Boehringer Ingelheim, Cytokinetics, Edwards Lifesciences, Eli Lilly, Janssen, Merck, and Novo Nordisk. BAB and SJA are named inventors (U.S. Patent no. 10,307,179) for the tools and approach for a minimally invasive pericardial modification procedure to treat heart failure. RCM consults for Alleviant, Corvia and HemodynamiQ. MJP reports consulting honoraria, speaker's fees and proctoring fees from Abbott Vascular and Boston Scientific, consulting honoraria from W.L. Gore, Biotronik, and Philips Medical, consulting honoraria and speaker's fees from Medtronic, consulting honoraria from Shockwave and Innovheart and equity in InterShunt. PG has grant support from the NIH (K76AG064428, R21AG077092, R24AG064025), has received consulting fees from Sensorum Health and Axon Therapies and has received personal fees for expert testimony related to heart failure. RVP reports consulting fees from ICA. VYR reports serving as a consultant to and receiving stock options from Axon Therapies and, unrelated to this manuscript, VYR also serves as a consultant for and has equity in Ablacon, Acutus Medical, Affera-Medtronic, Apama Medical-Boston Scientific, Anumana, APN Health, Aquaheart, Atacor, Autonomix, Backbeat, BioSig, CardiaCare, CardioNXT/AFTx, Circa Scientific, CoRISMA, Corvia Medical, Dinova-Hangzhou DiNovA EP Technology, East End Medical, EPD-Philips, EP Frontiers, Epix Therapeutics-Medtronic, EpiEP, Eximo, Farapulse-Boston Scientific, Field Medical, Focused Therapeutics, HRT, Intershunt, Javelin, Kardium, Keystone Heart, LuxMed, Medlumics, Middlepeak, Neutrace, Nuvera-Biosense Webster, Oracle Health, Restore Medical, Sirona Medical, SoundCath, Valcare; and, unrelated to this work, has served as a consultant for Abbott, AtriAN, Biosense-Webster, BioTel Heart, Biotronik, Boston Scientific, Cairdac, Cardiofocus, Cardionomic, CoreMap, Fire1, Gore & Associates, Impulse Dynamics, Medtronic, Novartis, Philips, Pulse Biosciences and has equity in DRS Vascular, Manual Surgical Sciences, Newpace, Nyra Medical, Surecor, and Vizaramed. DB reports consulting fees and grant support from Axon Therapies. MRP is a consultant to Axon Therapies. SIS is an employee of Axon Therapies. SJS reports support from research grants from the National Institutes of Health (U54 HL160273, R01 HL107577, R01 HL127028, R01 HL140731, and R01 HL149423), Pfizer and AstraZeneca and consulting fees from Abbott, AstraZeneca, Amgen, Aria CV, Axon Therapies, Bayer, Boehringer-Ingelheim, Boston Scientific, Bristol Myers Squibb, Cyclerion, Cytokinetics, Edwards Lifesciences, Eidos, Imara, Impulse Dynamics, Intellia, Ionis, Lilly, Merck, Metabolic Flux, MyoKardia, NGM Biopharmaceuticals, Novartis, Novo Nordisk, Pfizer, Prothena, Regeneron, Rivus, Sardocor, Shifamed, Tenax, Tenaya, and United Therapeutics. All other authors have nothing to disclose., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)