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In the Chinese LEAP-Block randomized trial, patients with atrioventricular block, preserved ejection fraction and an expected high pacing burden had fewer composite clinical events with left bundle branch area pacing (LBBAP) than with right ventricular pacing at 24 months. The difference was driven mainly by fewer heart-failure events; the trial did not find a difference in death, device complications or upgrades to biventricular pacing.
A randomized trial in China found that left bundle branch area pacing (LBBAP) reduced a composite of death, heart-failure events or upgrade to biventricular pacing compared with right ventricular pacing among selected patients with atrioventricular block and preserved heart function. At 24 months, the estimated cumulative incidence was 5.0% with LBBAP and 13.2% with right ventricular pacing, according to the LEAP-Block study published in JAMA.
The study enrolled adults who needed a pacemaker and were expected to receive ventricular pacing more than 40% of the time. Participants had a left ventricular ejection fraction (LVEF) of at least 50% and were in sinus rhythm. In the modified intention-to-treat analysis, 482 patients were included, with an average age of 67 and an average LVEF of 64%. The trial ran at 14 hospitals in China.
At 24 months, the primary composite outcome occurred in 2.4% of the LBBAP group and 12.5% of the right ventricular pacing group in the reported event tally. The time-to-event analysis estimated cumulative incidence at 5.0% and 13.2%, respectively; the hazard ratio was 0.37 (95% confidence interval 0.19-0.73). The investigators reported that the composite difference was statistically significant and met the trial’s prespecified criteria for superiority.
The difference was driven mainly by fewer heart-failure events: 3.4% with LBBAP versus 11.3% with right ventricular pacing. The report said there was no difference in all-cause death, upgrade to biventricular pacing, device-related complications or pacing-induced cardiomyopathy. Acute implant success was 97.9% for LBBAP and 99.6% for right ventricular pacing. Left bundle branch capture was confirmed in 79.7% of LBBAP procedures.
Implications for Pacemaker Choice
The results add randomized evidence for choosing a pacing approach in people who have AV block, normal pumping function and are likely to depend substantially on ventricular pacing. Right ventricular pacing can alter the usual sequence of electrical activation; LBBAP aims to use the heart’s conduction system to preserve more coordinated contraction. The trial’s lower composite event rate suggests that this approach may reduce clinical problems for this particular group.
The result should not be read as proof that LBBAP is preferable for every person who needs a pacemaker. The outcome difference was largely attributable to heart-failure events, while the trial did not show a difference in deaths or several other individual outcomes. An outside expert, Fred Kusumoto of Mayo Clinic in Jacksonville, told MedPage Today that differences in clinicians’ decisions about diagnosing and treating heart failure could have influenced event counts. The findings inform clinical discussion but do not replace individual assessment of procedural risks, expected pacing burden and patient characteristics.
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Who the Trial Studied
LEAP-Block compared LBBAP with right ventricular pacing in adults with several forms of AV block, including complete block, Mobitz type II second-degree block, intermittent advanced block and symptomatic prolonged first-degree block. Of 551 people screened, 499 were randomized between 2021 and 2023. The final modified intention-to-treat cohort included 482 participants. Most patients assigned to right ventricular pacing received a septal lead rather than an apical one.
The trial addresses a population for whom guidance has been less strong than for patients with reduced ejection fraction. In 2023, the Heart Rhythm Society gave cardiac physiologic pacing a Class IIb recommendation—meaning it may be reasonable—for people with normal LVEF who are expected to need substantial ventricular pacing. The LEAP-Block authors described their participants as relatively low-risk compared with patients whose LVEF is below 50%, for whom guidelines give stronger recommendations favoring physiologic or biventricular pacing over conventional right ventricular pacing.
“These findings suggest that for patients with AVB and preserved cardiac function and a high anticipated ventricular pacing burden, LBBAP offers feasibility and safety comparable to those of RVP while reducing adverse clinical outcomes.”
— LEAP-Block study authors, as reported by MedPage Today
Limits of the Event Difference
The reported advantage was concentrated in heart-failure events, and the available report does not establish that LBBAP reduced mortality or the other individual components. Kusumoto cautioned that heart-failure event identification and treatment may vary with clinician behavior, which could affect comparisons. The trial also involved a relatively low-risk group with preserved LVEF, so its findings do not directly settle pacing choices for patients with reduced heart function.
The study report does not provide enough information here to determine how its results will translate across health systems, implanting teams or patient groups beyond those enrolled. Nor does the composite outcome by itself establish which pacing method is best for a specific patient. Longer-term outcomes and further evidence will help clarify the size and durability of any benefit.
Guidance and Longer-Term Follow-Up
The immediate next step for clinicians is to weigh the LEAP-Block results alongside existing guidance and each patient’s expected pacing burden, ejection fraction and procedural considerations. The trial adds evidence to the 2023 Heart Rhythm Society recommendation but, as a single study in a defined population, does not by itself settle practice for all AV block patients.
Further follow-up and studies in other patient populations can test whether the lower composite event rate persists over time and whether the heart-failure difference is reproduced. The available report does not state a specific upcoming guideline revision or additional LEAP-Block milestone. For now, the clearest finding is a 24-month reduction in the composite outcome in the studied group, driven chiefly by fewer recorded heart-failure events.
Key Questions
What did the LEAP-Block trial compare?
It compared left bundle branch area pacing with right ventricular pacing in patients with AV block, preserved LVEF and an anticipated ventricular pacing burden above 40%.
What was the main result?
At 24 months, the estimated cumulative incidence of the composite of death, heart-failure events or upgrade to biventricular pacing was 5.0% with LBBAP and 13.2% with right ventricular pacing. The trial reported that the difference met its criteria for superiority.
Which outcome mainly accounted for the difference?
The report attributed most of the difference to heart-failure events, recorded in 3.4% of the LBBAP group and 11.3% of the right ventricular pacing group. The study did not report a difference in all-cause death.
Does the result apply to everyone who needs a pacemaker?
No. Participants had AV block, sinus rhythm, preserved LVEF of at least 50% and an expected high pacing burden. The results do not directly establish the preferred approach for all pacemaker patients, including those with reduced ejection fraction.
Were there more device complications with LBBAP?
The report found no difference in device-related complications between the groups. Acute procedure success was 97.9% with LBBAP and 99.6% with right ventricular pacing.
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