Left Bundle Branch Area Antitachycardia Pacing Improves Success Rate Compared to Right Ventricular Antitachycardia Pacing

Authors, Journal, Affiliations, Type, DOI

• Authors: Emmanuel Offei, Yuki Ishidoya, Douglas Smego, Martha Sofia Ruiz Castillo, Muhammad S. Khan, Kyoichiro Yazaki, Ankur Shah, Ava Yektaeian Vaziri, Matthias Lange, Annie M. Hirahara, Hui Li, Gregory J. Stoddard, Ravi Ranjan, Derek J. Dosdall
• Journal: JACC: Clinical Electrophysiology 2026;12(6):1345–1355
• Affiliations: Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah; Departments of Biomedical Engineering, Surgery, and Internal Medicine (Division of Cardiovascular Medicine), University of Utah; Division of Epidemiology, University of Utah
• Type: Preclinical animal study (canine ischaemia-reperfusion model)
• DOI: 10.1016/j.jacep.2026.01.042

Overview

This preclinical study tested whether antitachycardia pacing (ATP) delivered through a left bundle branch area (LBBA) lead terminates ventricular tachycardia (VT) more effectively than conventional right ventricular (RV) apical ATP. In seven mongrel dogs with ischaemia-reperfusion injury, ICD leads were placed in the RV apex and the LBBA, and 79 inducible VT episodes were treated. LBBA ATP terminated VT in 70.2% of episodes versus 47.3% for RV ATP (risk ratio 1.44), without an increase in VT acceleration or degeneration to ventricular fibrillation. Activation mapping showed that LBBA ATP captured the Purkinje system earlier, reset the VT circuit in fewer beats (crossover point 4.1 vs 5.1 beats), and produced earlier Purkinje and myocardial activation. The study is mechanistic proof of concept for using an LBBAP lead as the ATP/shock lead in an ICD system.

Keywords

Antitachycardia pacing; Ischemia-reperfusion injury; Left anterior descending artery; Left bundle branch area

Key Takeaways

Methods

• Seven mongrel dogs (30.0 ± 2.1 kg, ~1 year old); one was excluded because it could not be resuscitated from VF during the first VT induction, leaving six animals for analysis.
• ICD leads implanted in the RV apex and the LBBA; left anterior descending artery occluded for 2 hours to produce ischaemia-reperfusion injury.
• Four days later, VT was induced by programmed pacing and burst ATP was delivered to the RV or LBBA lead for each episode.
• Left ventricular endocardial activation was mapped with an implanted basket catheter; Purkinje activations were identified from bipolar electrograms.
• Primary comparison: mixed-effects logistic regression with cluster-robust standard errors to account for repeated episodes per animal.

Electrophysiological effects

• QRS during LBBA capture was narrower than during RV capture: 70.6 ± 8.2 vs 111.0 ± 11.4 ms (P = 4 × 10⁻⁴).
• Eighty VT episodes were induced; one was excluded for competing ATP from both leads, leaving 79 (41 LBBA, 38 RV).
• Mean VT cycle length 180.0 ± 30.0 ms, similar between groups.

Efficacy and safety

• ATP success: 70.2% ± 10.2% with LBBA vs 47.3% ± 11.3% with RV; risk ratio 1.44 (95% CI 1.03–2.01), P = .040.
• No significant difference in VT acceleration or VF induction between LBBA and RV ATP.
• Primary success (single extra beat) and secondary success (multiple extra beats) were not significantly different.

Activation mapping and mechanism

• Crossover point — the beat at which the activation sequence correlates more with the ATP capture pattern than with the pre-therapy VT — occurred one beat earlier with LBBA ATP: 4.1 vs 5.1 beats (P = .047).
• Successful ATP had an earlier crossover than failed ATP: 3.7 vs 5.6 beats (P = 2.0 × 10⁻⁴).
• In successful episodes, Purkinje activation occurred earlier with LBBA ATP: 18.8 ± 5.4 vs 39.8 ± 5.6 ms (P = 8.4 × 10⁻⁸).
• Myocardial activation also occurred earlier: 25.7 ± 5.1 vs 38.7 ± 5.4 ms (P = 9.0 × 10⁻⁴).
• Purkinje activation preceded myocardial activation more often with LBBA ATP: 84.7% ± 10.7% vs 41.8% ± 8.3% (P = .002).
• The authors interpret this as direct engagement of the native conduction system, producing a more synchronous wavefront that disrupts the re-entrant circuit faster.

Clinical context

• Conventional RV ATP success is >80% for slower VT but only 52%–72% for fast VT (>188 beats/min).
• A prior study (LEADR) showed an LBBA lead with a shocking coil can be used safely, potentially eliminating the need for an RV shocking coil.
• The ischaemic lesion in this model was adjacent to the RV apical lead but spared the septal LBBA lead, so any anatomical bias favoured RV ATP — strengthening the LBBA result.

Limitations of the document

• Animal model, not human VT. All VT episodes were induced by programmed stimulation, which differs from spontaneous clinical VT; canine VT cycle lengths are shorter with a narrower excitable gap and are harder to terminate than typical human VT, so human success rates may be higher.
• Small sample: six analysed animals and 79 episodes; the study is powered for the primary comparison but not for subgroup or safety analyses.
• Immature infarct model. Four days after ischaemia-reperfusion is early; mature infarcts, heart failure remodelling and autonomic tone were not modelled.
• Species differences in Purkinje distribution and collateral circulation may limit translation.
• No clinical endpoint — the study measures acute ATP success, not shocks, mortality or quality of life.
• Mapping limitations: eight recordings were excluded for poor signal quality, and Purkinje identification was manual and morphology-based.
• Funding and conflicts: Medtronic donated ICDs, leads and programming equipment; one author consults for Abbott, Medtronic and Biosense Webster.

Key Concepts Mentioned

• entities/ICD — the therapy being tested
• concepts/Left-Bundle-Branch-Area-Pacing — the pacing site
• concepts/Wide-Complex-Tachycardia — the arrhythmia
• entities/ICD — the device platform
• concepts/Conduction-System-Pacing — the conduction network engaged by LBBA ATP

Key Entities Mentioned

• University of Utah — coordinating institution
• Medtronic — donated ICDs, pacing leads and CareLink SmartSync equipment
• OmniaSecure — the defibrillation lead evaluated in the companion LEADR trial

Wiki Pages Updated

• Created: wiki/sources/lbbap-atp-jaccep-2026.md
• Updated: wiki/entities/ICD.md
• Updated: wiki/concepts/Conduction-System-Pacing.md
• Updated: wiki/sourceindex.md
• Updated: log.md