OptimPacing trial: left bundle branch pacing cut event risk by 59% versus right ventricular pacing

Results of the international, multicenter OptimPacing trial were presented on November 8, 2026 at the American Heart Association Scientific Sessions in Chicago, according to newsroom.heart.org. The trial followed nearly 700 men and women with atrioventricular block who were treated with a pacemaker over a five-year period. It compared left bundle branch pacing with right ventricular pacing, the current standard. heart.orgnewsroom.heart.orgnewsroom.heart.orgOpen source ↗ The full manuscript was published the same day in NEJM.

At a planned interim analysis, left bundle branch pacing met the pre-established criteria for superiority. An independent monitoring committee and the study's steering committee then recommended ending the trial early.

Two pacing approaches

In atrioventricular block, electrical signals between the atria and the ventricles are delayed or interrupted. Symptoms include a very slow heart rate, fatigue, dizziness, fainting and chest pain, and in severe cases cardiac arrest.

Right ventricular pacing has been used routinely for decades to prevent bradycardia and cardiac arrest. However, pacing only the right side can make the lower chambers beat out of sync. Over time this may enlarge or weaken the heart muscle (pacing-induced cardiomyopathy) and contribute to heart failure in some people. heart.orgnewsroom.heart.orgnewsroom.heart.orgOpen source ↗ Left bundle branch pacing delivers the signal into part of the heart's own conduction pathway. It mimics the natural activation sequence, so the lower chambers contract in a more coordinated pattern.

Trial results

Left bundle branch pacing was associated with a 59% lower risk of death, heart failure hospitalization or cardiomyopathy. At four years, an estimated 8.5% of participants in this group had died, been hospitalized for heart failure or developed pacing-induced cardiomyopathy, versus 19.2% with right ventricular pacing.

No participant in the left bundle branch pacing group developed pacing-induced cardiomyopathy, compared with 11.7% in the right ventricular pacing group. Heart failure hospitalization occurred in 1.5% versus 2.9% of participants, respectively.

Study author Jiangang Zou of First Affiliated Hospital, Nanjing Medical University, said the difference between the groups was greater than the authors expected. In his view, left bundle branch pacing should be the first choice for patients with heart block who need a pacemaker. heart.orgnewsroom.heart.orgnewsroom.heart.orgOpen source ↗

The authors note that further research is needed to determine which technique suits which patients. It should also compare other approaches that follow the heart's natural electrical system and examine long-term safety and cost-effectiveness.