Conduction System Pacing and AV Junction Ablation in Heart Failure With Atrial Fibrillation (SYNC AF-HTx)

Safety and efficacY of conductioN System paCing and Atrioventricular Junctional Ablation Combined With ICD Implantation in Patients With End-stage Heart Failure and Atrial Fibrillation Eligible for Heart Transplantation (SYNC AF-HTx) : Multicenter Prospective Randomized Controlled Trial

The purpose of this study is to evaluate the safety and efficacy of conduction system pacing (CSP) using left bundle branch pacing (LBBP) and atrioventricular junction (AVJ) ablation in patients with end-stage heart failure and permanent atrial fibrillation (AF). Participants who are candidates for heart transplantation or left ventricular assist device (LVAD) implantation will be randomized to either the SYNC group (ICD implantation combined with LBBP and AVJ ablation) or the control group (ICD implantation only). The investigators will compare clinical outcomes, including mortality and heart failure hospitalization, between the two strategies over a 1-year follow-up period.

Study Overview

• Status: Not yet recruiting
• Conditions: Heart Failure; Atrial Fibrillation; Defibrillators, Implantable
• Intervention / Treatment: Device: LBBP + AVJ Ablation with ICD; Device: ICD Only

Detailed Description

End-stage heart failure patients often face a poor prognosis due to comorbid permanent AF, which leads to irregular heart rates and worsens ventricular function. While implantable cardioverter-defibrillators (ICDs) are standard for preventing sudden cardiac death, they may not sufficiently prevent heart failure progression in patients with narrow QRS complexes. This study explores a "SYNC" strategy using LBBP and AVJ ablation to achieve ventricular synchronization and heart rate regularization. This is a multicenter, prospective, randomized (1:1), single-blind trial involving 120 participants.

Inclusion Criteria: Participants must have LVEF≤35%, permanent AF for >6 months, and be eligible for ICD implantation while awaiting heart transplantation or LVAD.

Intervention (SYNC Group): Participants receive an ICD with an LBBP lead (Medtronic SelectSecure™ 3830) and undergo AVJ ablation.

Control Group: Participants receive standard ICD implantation with a minimal ventricular pacing setting.

Follow-up: Clinical assessments, echocardiography, and device profiles will be monitored at baseline, 1, 3, 6, and 12 months post-procedure.

• Study Type: Interventional
• Enrollment (Estimated): 120
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: tae hoon kim, MD, PhD.; Phone Number: 82-2-2228-8467.; Email: thkimcardio@yuhs.ac

Study Locations

• South Korea
  • Seoul, South Korea
    • Division of Cardiology, Yonsei University College of Medicine.
    • Contact: tae hoon kim, MD, PhD; Phone Number: 82-2-2228-8467; Email: thkimcardio@yuhs.ac

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

Candidates for ICD implantation (primary or secondary prevention). Permanent AF (>6 months) unsuitable for or failed catheter ablation. End-stage heart failure considering heart transplant or LVAD. LVEF ≤ 35 within 6 weeks before enrollment. NYHA functional class ≥ II. On GDMT for at least 3 months. Age ≥ 19 years.

Exclusion Criteria:

Existing LVAD or prior heart transplantation. Indications for cardiac resynchronization therapy (CRT). History of mechanical tricuspid valve replacement. Expected survival≤ 12 months. Inability to comply with the study protocol.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: SYNC group; Combined procedure of ICD implantation, LBBP lead insertion, and AVJ ablation.	Device: LBBP + AVJ Ablation with ICD; Insertion of an LBBP lead (Medtronic SelectSecure™ 3830) and performing AVJ ablation to ensure heart rate regularization and ventricular synchronization
Active Comparator: Control group; Standard ICD implantation with minimal ventricular pacing strategy.	Device: ICD Only; Participants receive standard ICD implantation with a minimal ventricular pacing strategy

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Composite of all-cause mortality, heart failure hospitalization, or urgent heart transplantation	Occurrence of the first event among the composite components	Time Frame: Up to 12 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
All cause mortality	All cause deaths including cardiovascular and non-cardiovascular deaths.	Up to 12 months
Cardiovascular mortality	Cardiovascular death	Up to 12 months
Heart failure hospitalization	An unplanned outpatient or emergency department visit or inpatient hospitalization in which the patient presented with signs and symptoms consistent with heart failure and required intravenous therapy.	Up to 12 months
Urgent heart transplantation	Urgent heart transplantation	Up to 12 months
LV systolic function	LVEF measure by echocardiography	6months and 12months

Collaborators and Investigators

• Sponsor: Yonsei University

Study record dates

Study Major Dates

• Study Start (Estimated): January 1, 2026
• Primary Completion (Estimated): January 1, 2028
• Study Completion (Estimated): May 1, 2028

Study Registration Dates

• First Submitted: December 18, 2025
• First Submitted That Met QC Criteria: December 30, 2025
• First Posted (Estimated): January 12, 2026

Study Record Updates

• Last Update Posted (Estimated): January 12, 2026
• Last Update Submitted That Met QC Criteria: December 30, 2025
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Keywords: Heart Transplantation; ICD; Conduction System Pacing (CSP); End-stage Heart Failure; Left Bundle Branch Pacing (LBBP); Atrioventricular Junction Ablation (AVJ ablation)
• Additional Relevant MeSH Terms: Cardiovascular Diseases; Pathologic Processes; Heart Diseases; Arrhythmias, Cardiac; Pathological Conditions, Signs and Symptoms; Heart Failure; Atrial Fibrillation; Equipment and Supplies; Defibrillators; Electrodes; Electrical Equipment and Supplies; Electrodes, Implanted; Prostheses and Implants; Defibrillators, Implantable
• Other Study ID Numbers: 4-2025-1357

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No