Left Bundle-Branch Area Pacing Cut Heart Failure Events in AV Block. LEAP-Block Puts a Number on It.
In a 482-patient JAMA trial, left bundle-branch area pacing cut the 24-month composite to 2.4 percent, versus 12.5 percent with right ventricular pacing.
Left bundle-branch area pacing lowered the 24-month rate of death, heart failure events or upgrade to biventricular pacing to 2.4 percent, against 12.5 percent with right ventricular pacing, in patients with atrioventricular block and preserved ejection fraction, according to the LEAP-Block trial published in JAMA on Oct. 28.
Right ventricular pacing remains the default for many patients with AV block, but it activates the ventricles in a nonphysiologic way and may raise heart failure risk. LEAP-Block is a randomized test of whether pacing the conduction system instead changes hard outcomes, not just QRS width or echo measures.
Who was in the trial?
Patients who would be paced most of the time. The trial randomized 499 adults at 14 hospitals in China, led by investigators at Fuwai Hospital in Beijing, and analyzed 482 (242 left bundle-branch area pacing, 240 right ventricular pacing). According to the JAMA research summary, eligible patients had a left ventricular ejection fraction of 50 percent or more, sinus rhythm and an anticipated ventricular pacing burden above 40 percent. Persistent atrial fibrillation, a prior pacemaker and an ICD indication were exclusions. Mean age was 67 and 46 percent were women. All patients received a dual-chamber device, and endpoints were evaluated blinded.
The ClinicalTrials.gov record (NCT04730921) lists third-degree AV block, type II second-degree block, intermittent advanced block and symptomatic first-degree block with a PR interval of at least 250 ms among the qualifying indications.
What did it show?
A large relative reduction from a modest absolute base. The primary composite occurred in 2.4 percent of the conduction system pacing group and 12.5 percent of the right ventricular pacing group, an absolute difference of 10.1 percentage points (95% CI, 3.4 to 16.8; P = .003). The hazard ratio was 0.37 (95% CI, 0.19 to 0.73). Kaplan-Meier cumulative incidence at 24 months was 5.0 percent versus 13.2 percent.
Heart failure events drove the result: 8 patients (3.4 percent) versus 26 (11.3 percent). The trial found no significant differences in all-cause death, biventricular upgrade, device-related complications or pacing-induced cardiomyopathy. By The Script Pad's arithmetic from the reported rates, about 10 patients would need conduction system pacing instead of right ventricular pacing to prevent one primary event over two years, and about 13 to prevent one heart failure event.
The benefit came almost entirely from fewer heart failure events, in a single-country trial using one kind of lead. That is a strong signal, not yet a universal rule.
What are the caveats?
Several, and the authors name most of them. The trial was not powered to compare the individual components of the composite. Follow-up was 24 months. Left bundle-branch area pacing used a lumenless lead, so the results may not carry over to stylet-driven leads. A small number of randomized patients were excluded after randomization, which the summary says may have introduced limited selection bias. All sites were in China.
Acute procedural success was 97.9 percent with left bundle-branch area pacing and 99.6 percent with right ventricular pacing (P = .22), but left bundle-branch capture was confirmed in 188 of 236 patients, or 79.7 percent. In other words, about one in five patients assigned to the newer approach did not have confirmed bundle capture, a figure worth keeping in mind when comparing LEAP-Block with other series.
What it means in clinic
For patients with AV block, normal ejection fraction and an expected high pacing burden, the JAMA summary calls left bundle-branch area pacing "a reasonable pacing strategy when this type of pacing is available and feasible." General cardiologists and internists referring these patients can reasonably ask the implanting electrophysiologist whether conduction system pacing is offered, which lead is used and how capture is confirmed. Follow-up clinics should keep watching for heart failure symptoms in patients who already carry a right ventricular lead, since that is where the trial found the difference. This site has also covered an FDA early alert on a transcatheter valve delivery system and the PELICAN trial of cardiac index-guided therapy.
Reported, fact-checked and edited by The Script Pad's editorial staff. See How we use AI.
This article is for professional education and does not replace clinical judgment. Treatment decisions should be based on the individual patient and current guidelines.
