For patients with symptomatic obstructive hypertrophic cardiomyopathy (oHCM), the net effect of right ventricular pacing (RVP) has been variable. A new trial suggests that personalising the therapy by electromechanically optimising the atrio-ventricular delay (AVD) can provide a net benefit for symptoms and exercise capacity.¹
Right ventricular pacing can reduce the left ventricular outflow tract gradient (LVOTg) but may also decrease cardiac output, leading to inconsistent clinical outcomes.² The EMORI-HCM trial investigated whether optimising the AVD could resolve this variability and improve patient symptoms.
Methodology
The Electromechanically Optimized Right Ventricular Pacing in Obstructive Hypertrophic Cardiomyopathy (EMORI-HCM) study was a multicenter, blinded, randomized, crossover trial.¹ The study enrolled 60 patients with symptomatic oHCM who had an existing dual-chamber device and a resting or provoked LVOTg of at least 30 mm Hg.
Participants were randomized to one of two arms: 3 months of continuous AVD-optimized RVP followed by 3 months of backup-only RVP (control), or the reverse sequence. The AVD was optimised for each patient using a high-precision protocol that assessed acute changes in beat-by-beat blood pressure while varying the AVD.
The primary outcome was the change in symptoms measured by the Kansas City Cardiomyopathy Questionnaire Clinical Summary Score (KCCQ-CSS). Secondary outcomes included daily symptom scores collected via a smartphone app, patient preference, EQ-5D scores, exercise capacity, and LVOTg.
Results
Compared with backup-only pacing, AVD-optimized RVP resulted in a significant improvement in the primary endpoint, with the KCCQ-CSS increasing by 4.5 points (95% credible interval [CrI]: 1.3–8.1; probability of benefit [Pr(benefit)] = 0.997).
Significant improvements were also seen in several secondary outcomes. Daily symptom scores improved (OR: 1.29; 95% CrI: 0.98–1.68; Pr(benefit): 0.969), and exercise capacity increased by 1.0 mL/kg/min (95% CrI: 0.1–2.0; Pr(benefit): 0.984). Furthermore, the LVOTg was reduced by a mean of 7.3 mm Hg (95% CrI: −13.5 to −1.1; Pr(benefit): 0.010). The intervention had no effect on B-type natriuretic peptide levels, and ejection fraction was preserved.
In Practice
The findings from EMORI-HCM demonstrate that personalising RVP through electromechanical optimisation can achieve meaningful clinical improvements for patients with oHCM. The study authors concluded, “In patients with oHCM, RVP delivered at electromechanically optimized AVD improves symptoms and exercise capacity.”¹ This approach offers a potential strategy to enhance the efficacy of device-based therapy in this patient population.
References
1. Mohal JS, Whinnett ZI, Mohiddin SA, et al. Electromechanically Optimized Right Ventricular Pacing for Obstructive Hypertrophic Cardiomyopathy: The EMORI-HCM Trial. J Am Coll Cardiol. 2026;87(2):124-139. https://doi.org/10.1016/j.jacc.2025.08.050.
2. Arnold AD, Howard JP, Chiew K, et al. Right ventricular pacing for hypertrophic obstructive cardiomyopathy: meta-analysis and meta-regression of clinical trials. Eur Heart J Qual Care Clin Outcomes. 2019;5:321-333. https://doi.org/10.1093/ehjqcco/qcz006.
Disclaimer: The information presented in this article is for educational purposes only. Any quotes included reflect the opinions of the individual quoted, and do not necessarily reflect the views of the publisher. The publisher does not guarantee the accuracy or completeness of the content and accepts no responsibility for any errors, or any consequences arising from its use.