Left Bundle Branch Pacing vs Left Ventricular Septal Pacing vs Biventricular Pacing for Cardiac Resynchronization Therapy

Authors, Journal, Affiliations, Type, DOI

• Authors: Juan C. Diaz, Usha B. Tedrow, Mauricio Duque, Julian Aristizabal, Eric D. Braunstein, Jorge Marin, Cesar Niño, Oriana Bastidas, Nestor Lopez Cabanillas, Bruce A. Koplan, Carolina Hoyos, Carlos D. Matos, Daniela Hincapie, Alejandro Velasco, Nathaniel A. Steiger, Sunil Kapur, Thomas M. Tadros, Paul C. Zei, William H. Sauer, Jorge E. Romero
• Journal: JACC: Clinical Electrophysiology 2024;10(2):295–305
• Affiliations: Cardiac Arrhythmia Service, Clínica Las Vegas, Universidad CES (Medellín, Colombia); Brigham and Women's Hospital and Harvard Medical School (Boston); Clínica Las Américas (Medellín); Smidt Heart Institute, Cedars-Sinai (Los Angeles); Clínica SOMER (Rionegro, Colombia); Hospital Pablo Tobón Uribe (Medellín); Adventist Cardiovascular Institute (Buenos Aires); University of Texas Health Sciences Center (San Antonio)
• Type: Prospective multicentre observational registry
• DOI: 10.1016/j.jacep.2023.10.016

Overview

This prospective multicentre registry compared three pacing strategies for CRT — left bundle branch pacing (LBBP), left ventricular septal pacing (LVSP), and biventricular pacing (BIVP) — in 415 patients. LBBP was associated with significantly better freedom from the composite of heart failure hospitalisation and all-cause mortality than both LVSP (76.6% vs 48.4%) and BIVP (76.6% vs 43.6%), driven entirely by fewer heart failure hospitalisations; all-cause mortality did not differ. LVSP and BIVP had similar outcomes, suggesting that achieving true left bundle branch capture, rather than merely pacing the left septal endocardium, is what determines clinical benefit. LBBP also produced the narrowest paced QRS (117.5 ms), the shortest stimulus-to-LV activation time, the greatest LVEF improvement, and the highest rate of NYHA improvement. The finding reframes LBBAP as a spectrum in which LVSP should not be considered equivalent to LBBP.

Keywords

Cardiac resynchronization therapy, conduction system pacing, left bundle branch area pacing, heart failure

Key Takeaways

Population and procedure

• 415 patients: LBBP 141, LVSP 31, BIVP 243; median follow-up 399 days (IQR 249.5–554.8).
• Inclusion: guideline CRT indication — LVEF ≤35% with LBBB (Strauss), or LVEF <40% with expected RV pacing >40%, NYHA II–IV on GDMT.
• LBBAP was offered as first-line after informed consent; allocation was by patient and operator preference.
• LBBP was achieved in 82% (141/172) of intended LBBAP cases, versus 94.7% success for BIVP (P < .001).
• Median procedural time: LBBP 90 min, LVSP 100 min, BIVP 129 min (LBBP vs BIVP P < .001; LVSP vs BIVP P = .003).
• Median fluoroscopy: LBBP 11 min, LVSP 19 min, BIVP 21.7 min (LBBP vs LVSP P = .023; LBBP vs BIVP P < .001).
• Paced QRS: LBBP 117.5 ± 16.6 ms, LVSP 144.9 ± 15.8 ms, BIVP 150.3 ± 27 ms (LBBP vs both P < .001; LVSP vs BIVP P = .353).
• Stim-LVAT: LBBP 84 ms (IQR 75–94) vs LVSP 104 ms (IQR 100–120.5) (P < .001).
• Acute complications 0.7% overall (one septal perforation each in LBBP and LVSP, one pneumothorax in BIVP).

Clinical outcomes

• Freedom from the primary composite (HF hospitalisation or all-cause mortality): LBBP 76.6% vs LVSP 48.4% (HR 1.37, 95% CI 1.143–1.649, P = .001) and vs BIVP 43.6% (HR 1.43, 95% CI 1.175–1.730, P < .001).
• The LBBP advantage was driven by a 31.4% absolute increase in freedom from HF hospitalisation versus LVSP (83% vs 51.6%; HR 3.55, 95% CI 1.856–6.791, P < .001) and a 35.3% increase versus BIVP (83% vs 47.7%; HR 1.63, 95% CI 1.309–2.036, P < .001).
• All-cause mortality did not differ significantly (LBBP 88.7% freedom vs LVSP 80.6%, P = .282; vs BIVP 78.1%, P = .647); a Double-Cox sensitivity analysis confirmed no mortality difference.
• LVSP vs BIVP: no difference in the composite (HR 0.71, 95% CI 0.423–1.207, P = .209), HF hospitalisation or mortality.
• Multivariable analysis among LBBAP patients: LBBP vs LVSP HR 0.312 (95% CI 0.169–0.575), P < .001.

Secondary outcomes

• LVEF change: LBBP +8% (IQR 0–20), LVSP +1.5% (−3.5 to 10), BIVP +3% (0–10); LBBP vs LVSP P = .001, LBBP vs BIVP P < .001.
• Final LVEF: 36.1% ± 12.8% LBBP, 28.2% ± 11.4% LVSP, 31.4% ± 10.8% BIVP.
• Improvement ≥1 NYHA class: 87.9% LBBP, 61.3% LVSP, 67.9% BIVP (LBBP vs both P < .001).
• Long-term device complications: 11.3% LBBP, 9.7% LVSP, 15.6% BIVP (P = .167).

Interpretation

• LVSP and BIVP both rely on myocardial cell-to-cell conduction before engaging the conduction system; LBBP directly stimulates the left conduction system. The outcome gradient tracks whether LBB capture was achieved.
• LBBP did not require more procedural time than LVSP, so the benefit is not purchased with longer procedures.
• The authors argue that strategies to increase the rate of LBB capture (e.g. deflectable sheaths, more attempts) have the potential to improve CRT outcomes.

Limitations of the document

• Small sample, especially the LVSP arm (n = 31) — underpowered for the LVSP vs BIVP comparison and for mortality.
• Non-randomised, prospective registry with selection bias; consecutive enrolment reduces but does not eliminate it.
• LVSP is defined by exclusion of LBBP using criteria with high specificity but low sensitivity, so some patients may be misclassified.
• Anatomical heterogeneity of LVSP — the results may not apply to every septal site (basal, mid, apical), and proximity to the conduction system may vary.
• Short median follow-up (399 days) — insufficient to detect mortality differences, which typically require years.
• Single-author device relationship: one author is a Medtronic proctor for LBBAP; no other conflicts reported.
• No core-laboratory echocardiography and no blinded outcome adjudication.

Key Concepts Mentioned

• concepts/Left-Bundle-Branch-Area-Pacing — the umbrella technique
• concepts/Left-Bundle-Branch-Area-Pacing — the sub-type without LBB capture
• concepts/Left-Bundle-Branch-Area-Pacing — true conduction-system capture
• concepts/Cardiac-Resynchronization-Therapy — conventional CRT
• concepts/Cardiac-Resynchronization-Therapy — the clinical context
• concepts/Left-Bundle-Branch-Area-Pacing — the capture category used in later CSPOT analyses

Key Entities Mentioned

• Clínica Las Vegas / Universidad CES — lead site
• Brigham and Women's Hospital — lead US site
• Medtronic — manufacturer of the 3830 lead and C315HIS sheath; one author is a proctor

Wiki Pages Updated

• Created: wiki/sources/lbbp-lvsp-crt-jaccep-2024.md
• Updated: wiki/concepts/Left-Bundle-Branch-Area-Pacing.md
• Updated: wiki/concepts/Conduction-System-Pacing.md
• Updated: wiki/entities/CRT.md
• Updated: wiki/sourceindex.md
• Updated: log.md