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

Conditions

• Atrial Fibrillation (AF)
• Cardiomyopathies
• Heart Failure

Eligibility Criteria

Sex

ALL

Age

19 Years - N/A

Healthy Volunteers

Not accepted

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.
• 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.

Study Details

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.

Key Dates

First listed

May 1, 2026

Start date

Jun 30, 2026

Status verified

Apr 2026

Primary completion

Jun 30, 2029

Completion

Dec 31, 2029

Study Design

Enrollment

44 participants (estimated)

Allocation

RANDOMIZED

Intervention model

PARALLEL

Primary purpose

TREATMENT

Arms

• Experimental: LBBAP Group
  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.
• Active Comparator: CS Pacing Group
  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.

Primary Outcome Measure

Change from Baseline Left Ventricular Ejection Fraction (LVEF) at 12 Months [ Time Frame: Baseline (at the time of device implantation) and 12 months post-implantation ]

Central Contacts

• Tae-Hoon Kim, Professor
  +82-2-2228-8467
  [email protected]

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