This is a multi-center, prospective, single-blind, randomized controlled clinical trial to evaluate the efficacy and safety of Bachmann bundle pacing (BBP) in preventing new-onset atrial fibrillation (AF) in patients with chronic cardiac insufficiency who have indications for cardiac resynchronization therapy with left bundle branch pacing (CRT/LBBP) or implantable cardioverter defibrillator (ICD) implantation. A total of 110 eligible patients will be randomly assigned 1:1 to the BBP group or the traditional right atrial appendage (RAA) pacing group. All patients will receive guideline-directed medical therapy (GDMT) for at least 3 months and standardized follow-up for 12 months after device implantation. The primary endpoint is the incidence of new-onset AF within 12 months after implantation. Secondary endpoints include time to first new-onset AF, procedural success rate, changes in cardiac function parameters, and incidence of adverse events. This study aims to provide high-level evidence-based medical evidence for BBP as a new atrial pacing strategy to prevent AF in heart failure patients.
Background Chronic heart failure (HF) is a prevalent and prognostically poor cardiovascular disorder, with atrial fibrillation (AF) being the most common arrhythmia comorbid with HF. The bidirectional interaction between HF and AF forms a vicious cycle, significantly elevating the risks of mortality, hospitalization, and stroke in affected patients. Epidemiological data indicate that the cumulative incidence of AF following pacemaker implantation reaches 30-40%, a rate markedly higher than that in the general population without pacemaker implantation. Traditional right atrial appendage (RAA) pacing, the most widely used clinical atrial pacing approach, induces prolonged interatrial conduction, asynchronous atrial contraction, and hemodynamic perturbations, which predispose patients to AF. The Bachmann bundle represents the most physiological atrial pacing site; pacing in this region achieves synchronous activation of the left and right atria, producing a narrower P wave compared with sinus rhythm and traditional RAA pacing. While prior studies have suggested that Bachmann bundle pacing (BBP) may reduce the recurrence and progression of atrial arrhythmias, there remains a paucity of prospective randomized controlled trials investigating the efficacy of BBP in preventing new-onset AF in HF patients undergoing cardiac resynchronization therapy with left bundle branch pacing (CRT/LBBP) or implantable cardioverter defibrillator (ICD) implantation. Study Objectives The primary objective of this study is to determine whether BBP reduces the incidence of new-onset AF within 12 months of device implantation, compared with traditional RAA pacing, in HF patients with indications for CRT/LBBP or ICD implantation. Secondary objectives include evaluating the impact of BBP on the time to first new-onset AF, procedural safety, cardiac function parameters, electrophysiological indices, and clinical adverse events (including HF rehospitalization, all-cause death, and stroke) during the 12-month follow-up period. Study Procedures 1. Screening and Baseline Assessment Eligible patients are identified per predefined inclusion and exclusion criteria. Following written informed consent, baseline data are collected, including demographic characteristics, medical history, 12-lead electrocardiogram (ECG), 24-hour Holter monitoring, transthoracic echocardiography, New York Heart Association (NYHA) functional classification, 6-minute walk test results, and N-terminal pro-brain natriuretic peptide (NT-proBNP) levels. 2. Randomization Patients are stratified by implant device type (CRT/LBBP or ICD) and randomized in a 1:1 ratio to the BBP group or the RAA pacing group via a central randomization system. 3. Intervention Patients in the BBP group undergo atrial lead implantation at the Bachmann bundle region, identified via anatomical localization and intracardiac electrogram recording. Successful BBP is defined by characteristic ECG changes: a positive P wave in leads I, II, III, and aVF; a biphasic or negative P wave in lead V1; a P wave duration narrowed by \>10 ms compared with baseline (in patients with pre-existing interatrial block); and documentation of the Bachmann bundle potential. If BBP implantation fails, the patient is immediately converted to RAA pacing, with the cause of failure recorded in detail. Intraoperative pacing parameters (threshold, sensing, impedance) are monitored in both groups. 4. Follow-up All patients undergo follow-up assessments at 1 week, 3 months, 6 months, 9 months, and 12 months post-implantation. Follow-up evaluations include ECG, 24-hour Holter monitoring, pacemaker programming, echocardiography, NYHA classification reassessment, 6-minute walk test, NT-proBNP measurement, medication adjustment tracking, and adverse event reporting. 5. Statistical Analysis All data are analyzed in accordance with the intention-to-treat (ITT) principle. The primary endpoint is compared using analysis of covariance, and the time to first new-onset AF is evaluated via the Kaplan-Meier method with log-rank testing. Continuous variables are compared using the t-test or Wilcoxon rank-sum test, while categorical variables are analyzed with the chi-square test or Fisher's exact test. A two-sided P value \< 0.05 is considered statistically significant.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
SINGLE
Enrollment
140
A minimally invasive endocardial pacing procedure where an atrial lead is placed at the Bachmann bundle region (located at the junction of the right atrium and left atrial appendage) under fluoroscopic and intracardiac electrogram guidance. Successful implantation is confirmed by characteristic ECG changes (positive P wave in leads I/II/III/aVF, biphasic/negative P wave in V1, P wave duration reduction \>10 ms in patients with interatrial block) and recording of the Bachmann bundle potential.
The standard clinical atrial pacing procedure where an atrial lead is implanted in the right atrial appendage via transvenous access, guided by fluoroscopy. Pacing parameters (threshold, sensing, impedance) are optimized intraoperatively to ensure stable atrial capture, consistent with current clinical practice guidelines for cardiac pacing in heart failure patients.
Fuwai Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences
Beijing, Beijing Municipality, China
Incidence of New-Onset Atrial Fibrillation
The proportion of patients who develop new-onset atrial fibrillation (AF) confirmed by 12-lead ECG or 24-hour Holter monitoring within 12 months after cardiac pacing device implantation. New-onset AF is defined as the first documentation of AF with a duration ≥30 seconds in patients with no prior history of AF or paroxysmal AF (documented ≥3 months before enrollment).
Time frame: 12 months after device implantation
Time to Onset of New-Onset Atrial Fibrillation Post-Device Implantation
Time from CRT/LBBP or ICD implantation to the first documentation of new-onset atrial fibrillation (AF) confirmed by 12-lead ECG or 24-hour Holter monitoring, with AF defined as an episode lasting ≥30 seconds. Time is recorded in days and analyzed using Kaplan-Meier survival methods.
Time frame: Up to 12 months after device implantation
Immediate Success Rate of Bachmann Bundle Pacing and Perioperative Complication Rate
Immediate success of Bachmann bundle pacing is defined as stable lead placement with successful atrial capture and characteristic ECG changes intraoperatively; perioperative complications (occurring within 30 days post-surgery) include lead dislodgement, pneumothorax, cardiac tamponade, and pocket hematoma, with incidence calculated as the proportion of patients with at least one complication in each group.
Time frame: Intraoperatively (success rate) and 30 days post-implantation (perioperative complications)
Absolute and percentage change in left atrial diameter/volume index from baseline to 12 months
Absolute and percentage changes in left atrial diameter (mm) and left atrial volume index (mL/m²) measured by transthoracic echocardiography at 12 months post-implantation compared with baseline.
Time frame: Baseline and 12 months after device implantation
Change in mitral/tricuspid regurgitation grade from baseline to 12 months
Change in mitral and tricuspid regurgitation grade (graded 0-IV) measured by transthoracic echocardiography at 12 months post-implantation compared with baseline.
Time frame: Baseline and 12 months after device implantation
Absolute change in left ventricular end-diastolic diameter (LVEDD) from baseline to 12 months
Absolute change in LVEDD (mm) measured by transthoracic echocardiography at 12 months post-implantation compared with baseline.
Time frame: Baseline and 12 months after device implantation
Absolute change in left ventricular end-systolic volume (LVESV) from baseline to 12 months
Absolute change in LVESV (mL) measured by transthoracic echocardiography at 12 months post-implantation compared with baseline.
Time frame: Baseline and 12 months after device implantation
Change in New York Heart Association (NYHA) functional class from baseline to 12 months
Change in NYHA functional class (graded I-IV) at 12 months post-implantation compared with baseline.
Time frame: Baseline and 12 months after device implantation
Absolute change in 6-minute walk test (6MWT) distance from baseline to 12 months
Absolute change in 6MWT distance (meters) at 12 months post-implantation compared with baseline
Time frame: Baseline and 12 months after device implantation
Absolute change in plasma NT-ProBNP level from baseline to 12 months
Absolute change in plasma NT-ProBNP level (pg/mL) measured by chemiluminescent immunoassay at 12 months post-implantation compared with baseline.
Time frame: Baseline and 12 months after device implantation
Comparison of P-wave duration from baseline to 12 months
Comparison of P-wave duration (ms) in the supine position (mean of 3 consecutive readings) between baseline and 12 months post-implantation
Time frame: Baseline and 12 months after device implantation
Comparison of P-wave amplitude from baseline to 12 months
Comparison of P-wave amplitude (mV) in the supine position (mean of 3 consecutive readings) between baseline and 12 months post-implantation
Time frame: Baseline and 12 months after device implantation
Comparison of P-wave vector from baseline to 12 months
Comparison of P-wave vector in the supine position between baseline and 12 months post-implantation.
Time frame: Baseline and 12 months after device implantation
Prevalence of interatrial block at baseline and 12 months
Prevalence of interatrial block (diagnosed by ECG criteria) in the supine position between baseline and 12 months post-implantation
Time frame: Baseline and 12 months after device implantation
Comparison of ventricular pacing threshold from baseline to 12 months
Comparison of ventricular pacing threshold (V) in the supine position (mean of 3 consecutive readings) between baseline and 12 months post-implantation.
Time frame: Baseline and 12 months after device implantation
Comparison of sensing threshold from baseline to 12 months
Comparison of sensing threshold (mV) in the supine position (mean of 3 consecutive readings) between baseline and 12 months post-implantation
Time frame: Baseline and 12 months after device implantation
Comparison of lead impedance from baseline to 12 months
Comparison of lead impedance (Ω) in the supine position (mean of 3 consecutive readings) between baseline and 12 months post-implantation.
Time frame: Baseline and 12 months after device implantation
Incidence of Procedure Complications Within 12 Months Post-Implantation
Cumulative incidence of long-term surgical complications (including lead fracture, chronic pocket infection, lead dislodgement, and cardiac perforation) within 12 months post-implantation, with complications adjudicated by an independent committee using VARC-3 criteria for severity and causality.
Time frame: 12 months after device implantation
Incidence of Heart Failure Rehospitalization, All-Cause Death, and Stroke Within 12 Months
Cumulative incidence of heart failure rehospitalization (unplanned admission for worsening HF), all-cause mortality, and ischemic/hemorrhagic stroke within 12 months post-implantation. All events are documented via medical records and confirmed by the study team.
Time frame: 12 months after device implantation
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