Left bundle branch pacing reduced deaths, heart failure hospitalizations, and cardiomyopathy compared to traditional right ventricular pacing in patients with atrioventricular block, according to clinical trial data presented at the American Heart Association Scientific Sessions in Chicago.
OptimPacing Trial Results for Atrioventricular Block
The investigator-initiated, international, open-label, randomized OptimPacing trial evaluated 702 patients requiring permanent pacemaker implantation due to high ventricular pacing burden. Researchers set out to determine whether targeting the left bundle branch could overcome the physiological limitations associated with traditional pacing methods. Jiangang Zou, MD, PhD, professor of cardiology at First Affiliated Hospital, Nanjing Medical University in China, noted the limitations of standard approaches during a presentation reported by healio.com.
“Right ventricular pacing is traditional pacing for heart block, but it’s associated with left ventricular dyssynchrony and left ventricular systolic dysfunction, increasing pacing-induced cardiomyopathy, heart failure and mortality. However, left bundle branch pacing is a novel physiological pacing. It can preserve the left ventricular synchrony, but its clinical benefits relative to right ventricular pacing remain uncertain,” Jiangang Zou said.
Investigators planned an interim analysis after at least 50 primary outcome events occurred. Following 51 primary outcome events at a median follow-up of 35.1 months, the trial terminated early due to the proven superiority of left bundle branch pacing.
Pacemaker Leads Target the Left Bundle Branch to Sync Ventricles
- Targeting Location: Placing pacemaker leads directly onto the heart’s natural electrical highway—the left bundle branch—keeps the left and right ventricles beating in sync, preventing the mechanical strain caused by older pacing methods.
- Reduced Risks: The trial demonstrated a sharp drop in adverse events, with patients experiencing fewer heart failure hospitalizations and zero instances of pacing-induced cardiomyopathy over the median follow-up period.
- Stable Performance: Measurements of electrical stability, including R-wave sensing, impedance, and capture thresholds, remained steady and reliable in both pacing groups.
Left Bundle Branch Pacing Reduces Primary Outcome Events
Out of the enrolled cohort, 685 patients with a mean age of 68 years and a male representation of 58% were included in the modified intention-to-treat analysis. The primary outcome measured a composite of all-cause death, heart failure hospitalization, or pacing-induced cardiomyopathy.
At the interim analysis, 16 patients assigned to left bundle branch pacing experienced a primary outcome event, compared to 35 patients in the right ventricular pacing group. This translated to a Kaplan-Meier 4-year cumulative incidence of 8.5% versus 19.2% (HR = 0.41; 95% CI, 0.23-0.75; P by stratified log-rank test = .003), as reported by healio.com.
| Outcome Metric | Left Bundle Branch Pacing | Right Ventricular Pacing |
|---|---|---|
| Primary Outcome Incidence (4-Year Cumulative) | 8.5% | 19.2% |
| Heart Failure Hospitalization | 1.5% | 2.9% |
| All-Cause Mortality | 7.4% | 7.7% |
While all-cause mortality rates remained similar between the two cohorts at 7.4% for left bundle branch pacing and 7.7% for right ventricular pacing, the structural heart improvements were distinct. Left ventricular end-diastolic volume and end-systolic volume were lower in the left bundle branch group, while left ventricular ejection fraction was higher.
Elaine Wan, MD, the Esther Aboodi Associate Professor of Medicine in Cardiology and Cardiac Electrophysiology at Columbia University Medical Center, discussed the potential impact of these findings on future medical standards during post-presentation commentary covered by healio.com.
“What we’ve learned here from this clinical trial, as we’ve learned when we buy a car or buy a house, is that location, location, location is very important. Here we’re showing that more physiological pacing instead of the traditional right ventricular pacing has shown benefit for physiological pacing,” Elaine Wan said.
Wan also noted that current guidelines from 2023, issued by the Heart Rhythm Society, Asia Pacific Heart Rhythm Society, and Latin American Heart Rhythm Society, classify ventricular pacing for patients requiring high pacing burdens as a class IIa recommendation. Manuscript reviews and larger upcoming trials will determine whether conduction system pacing shifts standard electrophysiology practices globally.
Future Directions in Cardiac Electrophysiology
The findings from the OptimPacing trial, presented at the American Heart Association Scientific Sessions running from November 6 to November 9, 2026, provide rigorous clinical evidence supporting left bundle branch pacing as a viable first-line strategy.
References
- Zou, J., et al. LBS.04. Late-breaking science: Innovations to optimize arrhythmia care. Presented at the American Heart Association Scientific Sessions, Chicago, Nov. 6-9, 2026.
- Heart Rhythm Society, Asia Pacific Heart Rhythm Society, and Latin American Heart Rhythm Society. 2023 Guidelines for Cardiac Pacing and Cardiac Resynchronization Therapy.
