A pacemaker technique that follows the heart's natural electrical wiring sharply reduced deaths, heart failure hospitalizations and pacing-induced heart muscle weakness compared with the decades-old standard approach, according to late-breaking research presented at the American Heart Association's Scientific Sessions 2026 in Chicago.
The international, multicenter OptimPacing trial followed 685 adults with atrioventricular block, a condition in which electrical signals between the heart's upper and lower chambers are delayed or interrupted, causing a very slow heart rate, fatigue, dizziness, fainting and, in severe cases, cardiac arrest. The standard treatment is a pacemaker that paces only the right ventricle, which can make the lower chambers beat out of sync and, over time, enlarge or weaken the heart muscle.
Left bundle branch pacing instead sends the signal into part of the heart's own conduction pathway, mimicking its natural activation sequence. At four years, an estimated 8.5% of participants receiving left bundle branch pacing had died, been hospitalized for heart failure or developed pacing-induced cardiomyopathy, compared with 19.2% in the right ventricular pacing group, a 59% lower risk. No participants in the left bundle branch pacing group developed pacing-induced cardiomyopathy, versus 11.7% in the standard group, and heart failure hospitalization occurred in 1.5% versus 2.9%.
An independent monitoring committee reached the superiority threshold at a planned interim analysis after a median three-year follow-up and recommended ending the trial early, a decision the steering committee endorsed. The results were simultaneously published as a full manuscript in the peer-reviewed New England Journal of Medicine; the abstract is available through the meeting's Online Program Planner.
"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, M.D., Ph.D., a professor of cardiology at First Affiliated Hospital, Nanjing Medical University in Nanjing, China. He said the technique should be the first choice for patients with heart block who need a pacemaker.
The trial ran at 17 centers across mainland China, Hong Kong, the United Kingdom, Poland and the United States from June 2021 to January 2025. Participants averaged 68.4 years old, and most began with normal left ventricular ejection fraction. The researchers acknowledged limitations: early termination could overestimate benefits and reduce precision, findings may not apply to people with already reduced heart function, and all procedures used a single type of lead, leaving questions about other tools.
The implications extend beyond one device choice. Heart block is a common reason for pacemaker implantation, and pacing-induced cardiomyopathy is a recognized long-term complication that drives atrial fibrillation patients and others toward heart failure care. Zou called for research comparing pacing approaches that follow the heart's natural electrical system and examining long-term safety and cost-effectiveness to inform guideline updates. The findings were presented at Scientific Sessions 2026, a premier global exchange of cardiovascular science, and the association notes that meeting abstracts are not peer-reviewed and findings are preliminary until journal publication. Financial information about the association is available here, and additional resources accompany the release on NEWMEDIAWIRE. Related association coverage includes Reconditioned pacemakers worked as well as new ones and Lifestyle & risk factor changes improved AFib symptoms, not burden, over standard care, while broader patient resources are available at stroke.org.
