Trials Bolster LBBAP as an Alternative to Biventricular Pacing in CRT

The evidence around conduction-system pacing, especially left bundle branch area pacing (LBBAP), as an option for patients who require cardiac resynchronization therapy (CRT) continues to mature, as highlighted by three studies presented recently at the European Heart Rhythm Association (EHRA) Congress 2026 in Paris, France.

The LECART trial showed improved outcomes with LBBAP versus conventional biventricular (BiV) pacing, driven by a reduction in device-related complications requiring surgical reintervention.

The LEFT-BUNDLE-CRT trial fell shy of establishing the noninferiority of LBBAP compared with BiV pacing in terms of CRT response, although response rates were high in both groups and clinical outcomes were similar.

And finally, extended follow-up of the His-Alternative I pilot study showed that His-bundle pacing had results comparable to those achieved with BiV pacing over the long term as long as implant thresholds were low.

Together, “these studies move the field forward, but in a nuanced rather than a simplistic way,” Elena Arbelo, MD, PhD (Hospital Clínic de Barcelona, Spain), chair of EHRA’s advocacy and quality improvement committee, commented to TCTMD via email.

“We now have randomized data showing that [LBBAP] is a very credible CRT option, with procedural advantages in some settings and clinical outcomes that are at least broadly comparable to BiV-CRT in selected populations,” she said. “But I would still be cautious about overinterpreting the current evidence. These trials are important, but they do not yet justify a one-size-fits-all conclusion that LBBAP should replace conventional CRT across the board.”

Although conduction-system pacing has emerged over the past several years as an alternative to BiV pacing in patients who require CRT, there remains a lack of definitive randomized evidence supporting the approach. Just last month, in fact, two RCTs provided conflicting results. Currently, pacing and CRT guidelines from the European Society of Cardiology state that “especially in CRT candidates with LBBB [left bundle branch block], biventricular pacing has more solid evidence of efficacy and safety, and therefore remains first-line therapy.”

LECART

At EHRA 2026, Jean-Benoît le Polain de Waroux, MD, PhD (AZ Sint-Jan, Bruges, Belgium), presented results from the LECART trial, which was conducted at 11 centers in Belgium with extensive experience in both conduction-system and BiV pacing.

The trial included 168 patients (median age 71 years; 33% women) with heart failure with reduced ejection fraction (HFrEF), a wide QRS, and no right bundle branch block who had an indication for a CRT defibrillator or pacemaker. They were randomized to LBBAP using stylet-driven leads or BiV pacing. The crossover rates were 6% in the LBBAP arm and 7% in the BiV pacing arm.

About 20% of patients had ischemic cardiomyopathy, and 79% had typical LBBB. Median LVEF was 30.5%.

The primary endpoint, a composite of all-cause death, hospitalization for HF, any device-related complication requiring surgical reintervention, or failure to deliver CRT at 1 year, was 25% in the BiV pacing group and 12% in the LBBAP group (HR 2.14; 95% CI 1.01-4.52). The only individual component that endpoint to differ between groups was complications leading to reintervention—15% with BiV pacing and 2% with LBBAP (OR 6.76; 95% CI 1.48-30.97).

LBBAP was performed with a shorter median procedure time (76 vs 98 min) and fluoroscopy time (9 vs 12 min; P = 0.007 for both). It also resulted in a significantly greater reduction in QRS duration at 3, 6, and 12 months (P < 0.001 for all).

Both pacing types provided similar improvements in NYHA class, 6-minute walk distance, quality of life, LVEF, NT-proBNP, and LV reverse remodeling.

“Left bundle branch area pacing appears to provide an effective and practical strategy for cardiac resynchronization,” le Polain de Waroux said.

Arbelo said the superiority of LBBAP demonstrated in the trial should be interpreted carefully since the composite endpoint combined hard outcomes with others like reintervention and CRT implant failure. “In practice, the apparent advantage seems to have been driven mainly by fewer reinterventions and better procedural efficiency, rather than by a clear difference in hard clinical events,” she said.

LEFT-BUNDLE-CRT

Óscar Cano Pérez, MD, PhD (Hospital Universitari i Politècnic La Fe, Valencia, Spain), presented results of the LEFT-BUNDLE-CRT trial, which were published simultaneously in the European Heart Journal. The noninferiority study, conducted at 11 centers in Spain, randomized 175 patients (median age 68 years; 33% women) with LBBB who had a class I or IIa guideline indication for CRT. About 28% of the cohort had ischemic cardiomyopathy, with a prolonged QRS duration seen in the LBBAP versus BiV pacing group at baseline (171 vs 165 ms; P = 0.04). Median LVEF was about 29%.

The primary outcome, assessed at 6 months, was CRT response, defined as an improved clinical composite score or at least a 15% reduction in LV end-systolic volume. This was observed in 90% of patients treated with LBBAP and 95% of those treated with BiV pacing (RR 0.95; 95% CI 0.88-1.02). This difference did not meet criteria for the noninferiority of LBBAP (P = 0.12 for noninferiority) because the lower bound of the confidence interval was lower than 0.90 (a 10% margin).

In an on-treatment analysis accounting for a high rate of crossover, however, LBBAP was noninferior to BiV pacing.

In the intention-to-treat analysis, the proportion of patients with an improved clinical composite score was high in both groups (77% with BiV pacing and 68% with LBBAP; P = 0.19), as was the percentage with at least a 15% reduction in LV end-systolic volume (85% vs 79%; P = 0.34).

There were no significant differences between trial arms in HF or CV hospitalization, ventricular arrhythmias, death, new-onset atrial fibrillation, or a composite of death or HF hospitalization. Procedure-related complications and those occurring during follow-up were comparable in the two groups.

These trials . . . do not yet justify a one-size-fits-all conclusion that LBBAP should replace conventional CRT across the board. Elena Arbelo

Arbelo said the difference between the intention-to-treat and on-treatment analyses “likely reflects a combination of crossover, the complexity of achieving consistent LBBAP delivery in all randomized patients, and perhaps also the fact that LBBAP is not a uniform intervention.”

Together, the findings of LECART and LEFT-BUNDLE-CRT “suggest that LBBAP is very promising and often very effective, but that the magnitude and nature of its benefit depend strongly on how success is defined and on how reproducibly the technique is delivered,” Arbelo said, adding that there is a need for “larger studies with longer-term follow-up and ‘proper outcomes’ (CV mortality, HF admissions, etc).”

Longer Follow-up for His-Bundle Pacing

Also at the meeting, Emil Anton Frandsen, MD (Copenhagen University Hospital – Rigshospitalet, Denmark), presented a poster with longer-term follow-up of the His-Alternative I pilot study, with the results published simultaneously in JACC: Clinical Electrophysiology.

As previously reported by TCTMD, the trial, which included 50 patients with symptomatic HF, an LVEF of 35% or less, and LBBB, supported His-bundle pacing as a viable option alongside BiV pacing in patients who required CRT. The extended follow-up study, with a median duration of 5.3 years, evaluated long-term lead performance, survival, and echocardiographic outcomes based on which type of pacing patients received—His-bundle pacing in 19 and BiV pacing in 31.

The extended follow-up showed that His-bundle pacing was associated overall with more lead revisions (37% vs 3%; P = 0.003) and generator replacements (47% vs 10%; P = 0.005) compared with BiV pacing. However, patients in the His-bundle pacing group who had low implant thresholds (no greater than 2.5 V per millisecond) had results that were similar to those seen with BiV pacing.

Long-term risk of all-cause mortality or HF hospitalization was no different between groups (HR 0.32; 95% CI 0.07-1.49), with similarly high rates of echocardiographic response in the His-bundle and BiV pacing groups (89% and 90%, respectively).

The researchers acknowledge in their paper that “the study population was small, requiring larger studies on His pacing from centers with high experience to validate the results.”

Even so, Arbelo said, this analysis “is a very useful reminder that long-term performance matters and that conduction-system pacing should not be treated as a single homogeneous category.”

Though long-term remodeling and clinical response were similar with either His-bundle or BiV pacing, overall interventions were more frequent in the former group, “largely because patients with higher implant thresholds had more lead revisions and generator replacements,” she said. “That is important because it tells us that the long-term success of conduction-system pacing is highly dependent on implantation quality and electrical parameters.”

Pacing Options Moving Forward

Even as the evidence base around conduction-system pacing grows, BiV pacing continues to have an important role, Arbelo said.

“It remains the best-established CRT strategy with the longest evidence base, and it will continue to be entirely appropriate for many patients and many centers,” she said. “I think the field is moving toward a model where conduction-system pacing takes a growing share, especially in centers with strong expertise, but not toward elimination of BiV-CRT. The real future is probably individualized CRT, where the best modality depends on anatomy, conduction pattern, operator expertise, and the ability to achieve a durable result.”

She underscored that not all LBBAP techniques are the same.

“One of the most interesting themes across these data is that outcomes may differ according to whether true conduction-system capture is achieved, and that technical details may be highly relevant,” Arbelo said. “That is where I think the field needs to go next: larger trials, longer follow-up, and more precise phenotyping of which patients benefit most from which CRT strategy.”