OptimPacing: left bundle branch pacing beat standard pacing for heart block, trial stopped early

The international OptimPacing trial, presented on 8 November 2026 at the American Heart Association’s Scientific Sessions in Chicago and published simultaneously in the New England Journal of Medicine, compared two pacemaker techniques for atrioventricular (heart) block, where electrical signals between the heart’s upper and lower chambers are delayed or interrupted.

Two ways to pace

Standard right ventricular pacing prevents a dangerously slow heartbeat but can make the lower chambers contract out of sync, which over time may weaken the heart muscle (pacing-induced cardiomyopathy). Left bundle branch pacing places the lead into the heart’s own conduction system, mimicking natural activation.

Results

The trial enrolled 685 adults (average age 68.4; 57.5% men) at 17 centers in mainland China, Hong Kong, the United Kingdom, Poland and the United States from June 2021 to January 2025; most had normal pumping function at baseline. At a planned interim analysis after a median of about 3 years:

• The combined outcome of death, heart-failure hospitalization or pacing-induced cardiomyopathy was 59% lower with left bundle branch pacing — an estimated 8.5% versus 19.2% at four years.
• No patient in the left bundle branch group developed pacing-induced cardiomyopathy, versus 11.7% with right ventricular pacing.
• Heart-failure hospitalization: 1.5% versus 2.9%.

An independent monitoring committee recommended stopping the trial early because the pre-set superiority threshold was met. Lead author Jiangang Zou of Nanjing Medical University said the technique should be the first choice for heart-block patients who need a pacemaker. An earlier JAMA trial (LEAP-BLOCK), covered on this site on 28 October, also studied this approach.

Limitations

Stopping early can overestimate benefit and reduce precision. Most participants had normal ejection fraction, so results may not apply to people with weakened hearts. All procedures used the same type of lead, so it is unclear whether results apply to other tools. Funding came from Chinese provincial and national research programs. Long-term safety and cost-effectiveness need more study. This is not personal medical advice — discuss pacing options with your cardiologist.