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. 2025 Aug 31:S0735-1097(25)07558-8.
doi: 10.1016/j.jacc.2025.08.050. Online ahead of print.

Electromechanically Optimized Right Ventricular Pacing for Obstructive Hypertrophic Cardiomyopathy: The EMORI-HCM Trial

Jagdeep S Mohal  1 , Zachary I Whinnett  2 , Saidi A Mohiddin  3 , James Malcolmson  3 , Perry Elliott  3 , Julian O M Ormerod  4 , Sanjay Prasad  5 , James S Ware  6 , Robert M Cooper  7 , Mark A Tanner  8 , Zohya Khalique  9 , Jaymin S Shah  10 , Daniel Keene  11 , Pannathorn Tangkongpanich  1 , Edward C Lewis  1 , Chet Sharma  1 , Rohin K Reddy  12 , Akriti Naraen  1 , Keenan Saleh  1 , Jack W Samways  1 , James P Howard  1 , Jessica Artico  1 , Prapa Kanagaratnam  1 , Darrel P Francis  1 , Rasha K Al-Lamee  1 , Amanda Varnava  1 , Matthew J Shun-Shin  1 , Ahran D Arnold  13
Affiliations

Electromechanically Optimized Right Ventricular Pacing for Obstructive Hypertrophic Cardiomyopathy: The EMORI-HCM Trial

Jagdeep S Mohal et al. J Am Coll Cardiol. .

Abstract

Background: Many patients with symptomatic obstructive hypertrophic cardiomyopathy (oHCM) have devices capable of right ventricular pacing (RVP). Although pacing can reduce left ventricular outflow tract gradient (LVOTg), it can also reduce cardiac output, so its net effect is variable.

Objective: We tested whether electromechanical optimization of the programmed atrio-ventricular delay (AVD) allows RVP to achieve a net benefit on symptoms.

Methods: EMORI-HCM (Electromechanically Optimized Right Ventricular Pacing in Obstructive Hypertrophic Cardiomyopathy) is a multicenter, blinded, randomized, crossover trial of AVD-optimized RVP in patients with symptomatic oHCM with resting or provoked gradient of at least 30 mm Hg. Patients with existing dual-chamber devices were randomized to either 3 months of continuous AVD-optimized RVP (intervention) followed by 3 months of backup-only RVP (control), or vice versa. AVD was optimized using a high-precision multiple-alternation protocol assessing acute change in beat-by-beat blood pressure while varying AVD. The primary outcome was symptoms measured by the Kansas City Cardiomyopathy Questionnaire Clinical Summary Score. Secondary outcomes include patient-reported daily symptom data collected using a dedicated smartphone application (ORBITA-app), dichotomous patient preference, EQ-5D, exercise capacity, and LVOTg. Patients were blinded to treatment allocation. Symptom assessments were self-administered. Outcome measures were recorded at baseline, crossover, and completion. Analysis was by Bayesian ordinal mixed modeling.

Results: Between October 2021 and October 2024, 117 screened patients met the inclusion criteria, of whom 60 were randomized. AVD-optimized RVP improved Kansas City Cardiomyopathy Questionnaire Clinical Summary Score (+4.5; 95% credible interval [CrI]: 1.3-8.1; probability of benefit [Prbenefit] = 0.997) and daily symptom scores (OR: 1.29; 95% CrI: 0.98-1.68; Prbenefit: 0.969) compared with backup-only pacing. AVD-optimized RVP improved exercise capacity (+1.0 mL/kg/min; 95% CrI: 0.1-2.0; Prbenefit: 0.984) and LVOTg (-7.3 mm Hg; 95% CrI: -13.5 to -1.1; Prbenefit: 0.010). It had no effect on B-type natriuretic peptide (Prbenefit: 0.893) and ejection fraction was preserved (Prbenefit: 0.409).

Conclusions: In patients with oHCM, RVP delivered at electromechanically optimized AVD improves symptoms and exercise capacity. (Electromechanically Optimized Right Ventricular Pacing in Obstructive Hypertrophic Cardiomyopathy [EMORI-HCM], NCT05257772).

Keywords: atrioventricular delay; hypertrophic cardiomyopathy; pacemaker.

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Conflict of interest statement

Funding Support and Author Disclosures The study was funded by the British Heart Foundation (BHF, FS/CRTF/21/24171). Dr Mohal (FS/CRTF/21/24171), Dr Samways (FS/CRTF/25/24768), Dr Naraen (FS/CRTF/23/24417), Dr Shun-Shin (FS/ICRF/24/26094), Dr Howard (FS/ICRF/22/26039), and Dr Saleh (FS/CRTF/23/24482) are supported by the BHF. Dr Arnold is supported by the Medical Research Foundation (MRF-FEL-AI-24-105). Additional funding for research infrastructure was provided by the Coronary Flow Trust and the National Institute for Health and Care Research Imperial Biomedical Research Centre. The Peart Rose Research Unit and Team facilitated this study. The HeartHive is funded by Cardiomyopathy UK, Sir Jules Thorn Charitable Trust (21JTA), the BHF Big Beat Challenge award (BBC/F/21/220106), and the Medical Research Council/National Institute of Health Research Rare Disease Research UK Cardiovascular Initiative (MR/Y008235/1). Drs Arnold, Whinnett, and Keene have received honoraria from Biotronik and Medtronic. Drs Whinnett, Keene, and Kanagaratnam have received research funding from Medtronic. Dr Ware has received research support from Bristol Myers Squibb; has acted as a paid advisor to Health Lumen, Tenaya Therapeutics, and Solid Biosciences; and is a founder with equity in Saturnus Bio. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.

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