Is Left Bundle Branch Area Pacing the Future of CRT?

 New Data Suggests Superior Outcomes Over Biventricular Pacing

Introduction

Cardiac resynchronization therapy (CRT) has long been dominated by biventricular (BiV) pacing, especially for patients with heart failure (HF) and reduced ejection fraction. But as physiological pacing gains momentum, left bundle branch area pacing (LBBAP) has emerged as a potentially superior alternative. Recent results from the International Collaborative LBBAP Study (I-CLAS) presented at Heart Rhythm 2025 further support this shift, offering compelling data favoring LBBAP over traditional BiV pacing.

LBBAP vs BiV: The Study at a Glance

The I-CLAS trial retrospectively analyzed outcomes of 2,579 patients (mean age 70 years, 32% women) with LVEF ≤50%, NYHA class II-IV HF, and QRS ≥130 ms or high ventricular pacing burden. After propensity-score matching, 780 well-balanced pairs were studied.

Key Clinical Outcomes:

• Primary Composite Endpoint (Death or HF hospitalization):

  • LBBAP: 22.2%

  • BiV: 30.8%

  • HR 0.81, 95% CI 0.66–0.99

• Heart Failure Hospitalization Alone:

  • LBBAP: 13.6%

  • BiV: 20.8%

  • HR 0.63, 95% CI 0.49–0.82

• All-Cause Mortality:

• LBBAP: 12.4%

• BiV: 18.2% (NS trend)

Improved Ventricular Function and Arrhythmia Burden

LBBAP showed significantly better LVEF improvement:

• +12% vs +9%

• More patients achieved LVEF gain ≥15% (36% vs 28%, P = 0.004)

Arrhythmic Events (LBBAP vs BiV):

• Non-sustained VT: 4.9% vs 10.9%

• Sustained VT/VF: 4.0% vs 8.1%

• ICD shocks: 3.7% vs 6.8%

• New-onset AF: 2.3% vs 8.5%

These findings underscore LBBAP’s ability to maintain more physiologic ventricular activation, reduce arrhythmogenicity, and potentially lower the need for antiarrhythmic therapies or device interventions.

Procedural Safety and Complications

LBBAP also had a lower procedural complication rate:

• Overall complications: 3.5% vs 6.5%

• Lower incidence of lead dislodgement, pericardial effusion, and infections

Image Source: ACC.org

Practice Implications and Remaining Questions

Despite favorable results, this study was nonrandomized, retrospective, and conducted in high-volume centers with LBBAP expertise. Thus, the generalizability to all clinical settings remains uncertain.

According to experts like Rajesh Kabra, MD, ongoing RCTs and long-term lead performance data are crucial before LBBAP becomes mainstream. Current pacing guidelines by ESC, EHRA, and HRS support conduction system pacing selectively, but individualized patient selection remains the best approach until randomized trial evidence matures.

Key Takeaways for Clinicians

• LBBAP significantly lowers HF hospitalizations and arrhythmic events compared to BiV pacing.

• It leads to greater LVEF improvement and fewer procedural complications.

• While promising, these data stem from observational studies; results from ongoing RCTs are awaited.

• Operator experience and patient anatomy are pivotal in successful LBBAP implantation.

• Until stronger data emerge, tailoring CRT strategy based on patient profile and institutional expertise is recommended.