People with heart block, a common heart rhythm disorder, experienced significantly fewer serious cardiac events when treated with a newer pacemaker technique called left bundle branch pacing compared to the standard right ventricular pacing, according to late-breaking science presented at the American Heart Association’s Scientific Sessions 2026. The findings, simultaneously published in the New England Journal of Medicine, prompted an independent monitoring committee to recommend ending the trial early due to clear superiority of the new approach.
Heart block, also known as atrioventricular block, occurs when electrical signals between the heart’s upper and lower chambers are delayed or interrupted, causing symptoms such as fatigue, dizziness, fainting, and in severe cases, cardiac arrest. For decades, the standard treatment has been a pacemaker that stimulates the right ventricle. While effective at preventing a dangerously slow heart rate, right ventricular pacing can cause the lower chambers to beat out of sync, potentially leading to heart failure and pacing-induced cardiomyopathy, a weakening of the heart muscle.
Left bundle branch pacing, in contrast, delivers electrical signals to part of the heart’s natural conduction system, mimicking a more coordinated contraction. The international OptimPacing trial, which enrolled 685 adults across 17 centers in China, Hong Kong, the United Kingdom, Poland, and the United States, compared the two approaches. Over a median follow-up of three years, the primary composite outcome of death, heart failure hospitalization, or pacing-induced cardiomyopathy occurred in 8.5% of participants receiving left bundle branch pacing versus 19.2% in the right ventricular pacing group—a 59% reduction in risk. Notably, no participants in the left bundle branch pacing group developed pacing-induced cardiomyopathy, compared with 11.7% in the standard group. Heart failure hospitalizations were also lower (1.5% vs. 2.9%).
“Not all pacing options are the same, and people who need a pacemaker to keep their heart beating properly should talk with their healthcare team about which pacing approach is appropriate for their condition,” said lead author Jiangang Zou, M.D., Ph.D., of Nanjing Medical University. “Our findings show that left bundle branch pacing helped the heart beat in a more natural way and was linked to fewer serious heart-related events.”
The trial’s early termination, while underscoring the magnitude of benefit, may overestimate the effect size, and the results primarily apply to patients with normal heart pumping function. All procedures used a single type of pacing lead, so generalizability to other tools is uncertain. The researchers call for further studies to refine patient selection and assess long-term safety and cost-effectiveness.
The findings were presented at Scientific Sessions 2026, a premier global exchange of cardiovascular science. The full abstract and Online Program Planner are available. This research could influence future guidelines, as noted in related AHA statements on atrial fibrillation management and cardiac implantable electronic devices. For more information, visit heart.org or stroke.org.
