Left bundle-branch pacing was associated with a 59% lower risk of death, heart failure hospitalization, or pacing-induced cardiomyopathy compared with conventional right ventricular pacing among patients with atrioventricular block, according to findings presented at the American Heart Association's Scientific Sessions 2026.
At 4 years, the estimated cumulative incidence of the composite outcome was 8.5% with left bundle-branch pacing vs 19.2% with right ventricular pacing.
The findings, detailed in an American Heart Association Newsroom release, came from the international OptimPacing trial, which included nearly 700 adults requiring permanent pacemakers. The study, simultaneously published in the New England Journal of Medicine, found a lower incidence of the composite outcome with left bundle-branch pacing, with fewer cases of pacing-induced cardiomyopathy and heart failure hospitalization reported in that group.
Researchers conducted the investigator-initiated, open-label, randomized controlled trial at 17 centers across mainland China, Hong Kong, Poland, the United Kingdom, and the United States between June 2021 and January 2025. Participants had second-degree or complete atrioventricular block or atrial fibrillation with a slow ventricular response and were expected to require ventricular pacing at least 20% of the time.
Of 702 randomized patients, 685 were included in the modified intention-to-treat analysis, with 342 assigned to left bundle-branch pacing and 343 to right ventricular pacing. Mean age was 68.4 years, 57.5% were men, and most had preserved left ventricular ejection fraction at baseline.
After a median follow-up of 35.1 months, the primary composite outcome occurred in 16 patients receiving left bundle-branch pacing vs 35 receiving right ventricular pacing. The difference met the trial's prespecified threshold for superiority, prompting an independent monitoring committee to recommend early termination.
Pacing-induced cardiomyopathy occurred in no patients receiving left bundle-branch pacing compared with 19 receiving right ventricular pacing. The estimated 4-year cumulative incidence was 0% vs 11.7%, respectively. Heart failure hospitalization occurred as a first event in 2 vs 7 patients, respectively, with estimated incidences of 1.5% vs 2.9%.
All-cause mortality was similar between groups, with 15 deaths following left bundle-branch pacing vs 13 following right ventricular pacing. Procedure-related complications occurred in 3.8% vs 3.2% of patients, respectively.
Unlike conventional right ventricular pacing, which can disrupt ventricular synchrony, left bundle-branch pacing activates the heart's native electrical conduction system to promote coordinated ventricular contraction.
"We expected that the group with left bundle branch pacing would do better than the group with right ventricular pacing. However, the difference between the two groups was greater than we expected," said study author Jiangang Zou, MD, PhD, of Nanjing Medical University, in the American Heart Association release.
Investigators cautioned that early termination could overestimate treatment benefits. Most participants had preserved ventricular function, limiting generalizability to patients with reduced ejection fraction. All left bundle-branch procedures used the same lead type, leaving uncertainty about outcomes with other pacing devices.
Sources: American Heart Association, New England Journal of Medicine
