LBBAP vs. CS Pacing for CRT in Permanent Atrial Fibrillation and Heart Failure (SYNC-AF)

NCT07560891 | Not Yet Recruiting DMC

• 1 other identifier: 4-2025-1786
• Study Type: interventional
• Target: 44
• Locations: 0 countries
• Sites: N/A

Brief Summary

This is a prospective, multicenter, randomized controlled trial comparing Left Bundle Branch Area Pacing (LBBAP)-based cardiac resynchronization therapy (CRT) with conventional coronary sinus (CS) lead-based CRT in patients with permanent atrial fibrillation (AF) and heart failure (HF) who meet indications for CRT device implantation. Atrial fibrillation and heart failure frequently coexist, and both rapid heart rate and its irregularity contribute to worsening cardiac function. Atrioventricular junction (AVJ) ablation combined with CRT (biventricular pacing) has been established as an effective strategy for rate control and cardiac resynchronization in this population, supported by Class I recommendation in the 2021 ESC guidelines. However, conventional biventricular CRT via the CS lead can induce artificial electrical dyssynchrony, particularly in patients with a narrow QRS complex, potentially limiting its benefit. Conduction system pacing (CSP), including LBBAP, has emerged as a physiologic alternative that directly stimulates the native conduction system, preserving synchronous ventricular activation. Recent evidence (ALTERNATIVE-AF trial) suggests CSP may be superior to biventricular CRT in permanent AF patients undergoing AVJ ablation. However, no randomized controlled trial has directly compared LBBAP-based CRT with CS lead-based CRT in this specific population. The SYNC-AF trial will randomize 44 patients (22 per arm) to either LBBAP or CS pacing for CRT. The primary endpoint is change in left ventricular ejection fraction (LVEF) at 12 months as assessed by echocardiography in a blinded core laboratory. Secondary endpoints include changes in QRS duration, major adverse clinical events, device/procedure-related complications, and ventricular arrhythmia burden.

Conditions

Cardiomyopathies; Atrial Fibrillation (AF); Heart Failure

Keywords

LBBAP; Left Bundle Branch Area Pacing; CRT; Cardiac Resynchronization Therapy; Permanent Atrial Fibrillation; Conduction System Pacing; AVJ Ablation; Heart Failure

Outcome Measures

Primary Outcomes (1)

• Change from Baseline Left Ventricular Ejection Fraction (LVEF) at 12 Months

  Change in left ventricular ejection fraction (LVEF) from baseline to 12 months post-implantation, as measured by transthoracic echocardiography performed and interpreted by a blinded independent central core laboratory. LVEF is assessed using the biplane Simpson method.

  Baseline (at the time of device implantation) and 12 months post-implantation

Secondary Outcomes (13)

• Proportion of patients with absolute LVEF increase ≥5% at 12 months

  12 months post-implantation

• Proportion of patients with absolute LVEF increase ≥10% at 12 months

  12 months post-implantation

• Change in QRS Duration From Baseline

  Immediately post-implant and at 12 months

• Time to First Treated Ventricular Arrhythmia

  Up to 12 months

• Composite of All-Cause Death and Heart Failure Hospitalization

  Up to 12 months (first occurrence)

Study Arms (2)

LBBAP Group

EXPERIMENTAL

Participants undergo CRT device implantation (CRT-P or CRT-D) with Left Bundle Branch Area Pacing (LBBAP) as the left ventricular lead strategy. LBBAP is attempted first; if not feasible, crossover to CS lead is permitted. AVJ ablation is performed per clinical indication.

Device: Left Bundle Branch Area Pacing (LBBAP) for CRT

CS Pacing Group

ACTIVE COMPARATOR

Participants undergo CRT device implantation (CRT-P or CRT-D) with conventional Coronary Sinus (CS) lead-based pacing as the left ventricular lead strategy. AVJ ablation is performed per clinical indication.

Device: Coronary Sinus (CS) Lead-Based Biventricular CRT

Interventions

Left Bundle Branch Area Pacing (LBBAP) for CRT DEVICE

CRT device (CRT-P or CRT-D) implantation using LBBAP as the left ventricular pacing lead. A pacing lead is advanced through the interventricular septum to achieve left bundle branch area capture, confirmed by pacing parameters and electrocardiographic criteria (RBBB-like pattern with short R-peak latency in V5/V6). RV lead is implanted in standard fashion. AVJ ablation may be performed per clinical indication.

LBBAP Group

Coronary Sinus (CS) Lead-Based Biventricular CRT DEVICE

CRT device (CRT-P or CRT-D) implantation using a conventional coronary sinus (CS) lead as the left ventricular pacing lead. The CS lead is advanced via the coronary sinus into a lateral or posterolateral cardiac vein to achieve biventricular pacing. RV lead is implanted in standard fashion. AVJ ablation may be performed per clinical indication.

CS Pacing Group

Eligibility Criteria

• Age: 19 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Age ≥19 years
• Indication for CRT (CRT-P or CRT-D) device implantation per current guidelines
• Permanent atrial fibrillation (with or without planned AVJ ablation)
• Ability to understand the purpose of the study and provide written informed consent

You may not qualify if:

• Prosthetic tricuspid valve
• Prior myocardial infarction involving the interventricular septal area
• Life expectancy less than 12 months
• Unable to comply with planned 12-month follow-up for any reason
• Pregnancy
• History of heart transplantation
• Persistent left superior vena cava (PLSVC)

Sponsors & Collaborators

• Yonsei University: lead

MeSH Terms

Conditions

Atrial Fibrillation; Heart Failure; Cardiomyopathies

Condition Hierarchy (Ancestors)

Arrhythmias, Cardiac; Heart Diseases; Cardiovascular Diseases; Pathologic Processes; Pathological Conditions, Signs and Symptoms

Central Study Contacts

Tae-Hoon Kim, Professor

CONTACT

+82-2-2228-8467; thkimcardio@yuhs.ac

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Masking Details: Open-label study. Participants, care providers, and investigators are not masked to treatment allocation. However, echocardiographic outcome assessors at the blinded central core laboratory are masked to treatment assignment.
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Two parallel arms: LBBAP group (experimental) vs. CS pacing group (active comparator). 1:1 randomization. Open-label design with blinded echocardiographic core lab assessment.

Study Record Dates

• First Submitted: April 23, 2026
• First Posted: May 1, 2026
• Study Start (Estimated): June 30, 2026
• Primary Completion (Estimated): June 30, 2029
• Study Completion (Estimated): December 31, 2029
• Last Updated: May 1, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will not share