An observational study in Heart Failure - NYHA II - IV, Left Bundle Branch Area Pacing and Left Bundle Branch Block, sponsored by University of Pecs. Not yet recruiting at 1 site in Hungary. Open to participants aged 18 Years to 100 Years. Per ClinicalTrials.gov, last updated 2026-07-10.
Sponsored by University of Pecs · Observational
The goal of this observational study is to evaluate the long-term clinical outcomes of physiologic cardiac resynchronization therapy (CRT) using conduction system pacing strategies compared with conventional biventricular CRT in patients with heart failure with reduced ejection fraction (HFrEF) and electrical dyssynchrony.
The main questions it aims to answer are:
Participants receiving physiologic CRT as part of routine clinical care will undergo standard follow-up evaluations, including electrocardiography, echocardiography, laboratory testing, and device interrogation. Clinical outcomes will be collected prospectively for 24 months and compared with a historical cohort of patients treated with conventional biventricular CRT.
The study will assess clinical outcomes, echocardiographic response, electrical resynchronization parameters, and device-related safety in a real-world heart failure population.
Background
Heart failure with reduced ejection fraction (HFrEF) is associated with substantial morbidity, mortality, and healthcare utilization despite continuous advances in guideline-directed medical therapy. Cardiac resynchronization therapy (CRT) has become an established treatment for patients with symptomatic HFrEF and electrical dyssynchrony. Conventional biventricular pacing improves ventricular synchrony and clinical outcomes; however, approximately one-third of treated patients do not achieve a satisfactory response.
Conduction system pacing (CSP), particularly left bundle branch area pacing (LBBAP), has emerged as a physiological pacing strategy capable of directly engaging the native His-Purkinje conduction system. Compared with conventional biventricular pacing, CSP may produce more physiological ventricular activation, narrower paced QRS complexes, improved electrical synchrony, and greater reverse ventricular remodeling. Nevertheless, evidence regarding its long-term effectiveness in routine clinical practice remains limited, particularly in heterogeneous populations with different conduction abnormalities.
Study Rationale
The RESYNC-PACE study was designed to evaluate the effectiveness of individualized physiologic cardiac resynchronization strategies in a real-world population of patients with HFrEF requiring CRT.
The study investigates two complementary physiologic CRT approaches according to the underlying conduction disturbance. In patients with typical left bundle branch block (LBBB), left ventricular lead implantation is guided by the qLV ratio to achieve optimal electrical resynchronization through individualized coronary sinus lead positioning. In patients with intraventricular conduction delay (IVCD), a conduction system pacing strategy is applied using left bundle branch area pacing. When conduction system pacing alone results in incomplete electrical correction, defined by a paced QRS duration greater than 130 ms, an additional coronary sinus left ventricular lead is implanted to establish Left Bundle Branch Area Pacing Optimized Cardiac Resynchronization Therapy (LOT-CRT).
This individualized treatment algorithm reflects contemporary physiological concepts of ventricular resynchronization rather than a single implantation strategy and represents the principal scientific concept investigated in the study.
Scientific Objectives
The study aims to determine whether physiologic CRT strategies provide superior long-term clinical outcomes compared with conventional biventricular CRT when implemented in routine clinical practice.
In addition to evaluating clinical outcomes, the study investigates the relationship between electrical resynchronization, ventricular reverse remodeling, myocardial scar characteristics assessed by cardiac magnetic resonance imaging, and long-term prognosis. Particular emphasis is placed on identifying imaging-, electrocardiographic-, and device-derived predictors of CRT response that may facilitate patient selection and optimization of resynchronization therapy.
Study Methodology
RESYNC-PACE is a single-center, ambispective observational cohort study performed at the University of Pécs Clinical Centre Heart Institute. Consecutive patients undergoing physiologic CRT constitute the prospective cohort, while a historical cohort of patients treated with conventional biventricular CRT serves as the comparator.
All therapeutic procedures are performed as part of routine clinical care using commercially available CE-marked cardiac implantable electronic devices according to their approved indications and current international guideline recommendations. The study does not introduce experimental devices or procedures beyond standard clinical practice but prospectively evaluates the clinical performance of an individualized physiological CRT algorithm.
The comprehensive study database integrates demographic, clinical, electrocardiographic, echocardiographic, cardiac magnetic resonance imaging, procedural, device-derived, and long-term follow-up data. This integrated approach enables detailed evaluation of the mechanisms underlying CRT response and supports the development of patient-specific resynchronization strategies.
Expected Clinical Significance
The RESYNC-PACE study is expected to generate real-world evidence regarding the effectiveness of conduction system pacing-guided CRT strategies and individualized resynchronization algorithms. The findings may improve patient selection, optimize implantation strategies for different conduction disorders, and contribute to the growing evidence supporting physiologic cardiac resynchronization therapy in patients with heart failure.
94 studies on the registry are indexed under Bundle-Branch Block; 30 are open to participants now.
This study's planned enrollment of 50 is below the median of 162 across 33 observational studies indexed under Bundle-Branch Block.
Browse Bundle-Branch Block studies →University of Pecs is the lead sponsor of 106 studies on the registry; 25 are open to participants now.
Counted across the registry records on this site, refreshed daily.
The study population consists of adult patients with heart failure with reduced ejection fraction (HFrEF) who are treated at the University of Pécs Clinical Centre Heart Institute and meet contemporary guideline indications for cardiac resynchronization therapy (CRT). Eligible participants have symptomatic heart failure despite guideline-directed medical therapy, left ventricular systolic dysfunction, and evidence of electrical dyssynchrony manifested by left bundle branch block (LBBB) or intraventricular conduction delay (IVCD). The prospective cohort includes patients undergoing conduction system pacing-based CRT as part of routine clinical care, while the historical control cohort includes patients previously treated with conventional biventricular CRT at the same institution. The study population represents a real-world heart failure population routinely referred for CRT implantation in tertiary cardiovascular care.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Left bundle branch block (LBBB), or Intraventricular conduction delay (IVCD).
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
LVEF (left ventricular ejection fraction)
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Life expectancy
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
LBBB Cohort (qLV-guided Cardiac Resynchronization Therapy) Patients in this cohort have symptomatic heart failure with reduced left ventricular ejection fraction and complete left bundle branch block (LBBB) according to contemporary guideline criteria. Cardiac resynchronization therapy is performed using a personalized implantation strategy guided by the qLV ratio, defined as the interval between QRS onset and local left ventricular activation divided by the intrinsic QRS duration. The left ventricular lead is positioned at the site with the longest achievable electrical delay to maximize resynchronization benefit. Patients receive either conventional biventricular CRT or LOT- CRT according to clinical decision-making and anatomical feasibility. The cohort is followed longitudinally to evaluate the relationship between qLV-guided lead placement, electrical resynchronization, reverse ventricular remodeling, heart failure hospitalization, and all-cause mortality.
Device: Physiologic cardiac resynchronization using conduction system pacing and selective LV lead optimization.
IVCD Cohort (Conduction System Pacing-Guided Resynchronization Strategy) Patients in this cohort have symptomatic heart failure with reduced left ventricular ejection fraction and intraventricular conduction delay (IVCD) without typical left bundle branch block morphology. The resynchronization strategy is guided by the degree of electrical correction achieved with conduction system pacing. During implantation, left bundle branch area pacing (LBBAP) is attempted and paced QRS duration is assessed. If conduction system pacing alone results in a paced QRS duration greater than 130 ms, a Left Bundle Branch Area Pacing Optimized Cardiac Resynchronization Therapy (LOT-CRT) system is implanted by adding a left ventricular lead to further improve ventricular synchrony. The cohort is followed longitudinally to evaluate the association between electrical resynchronization, reverse ventricular remodeling, heart failure hospitalization, and all-cause mortality.
Device: Physiologic cardiac resynchronization using conduction system pacing and selective LV lead optimization.
Conduction System Pacing-Guided Cardiac Resynchronization Therapy is an individualized resynchronization strategy used in patients with heart failure, reduced left ventricular ejection fraction, and electrical dyssynchrony. The intervention is based on direct recruitment of the native cardiac conduction system through left bundle branch area pacing (LBBAP). During implantation, electrical resynchronization is assessed using electrocardiographic and device-derived parameters. In patients with intraventricular conduction delay or incomplete electrical correction, additional left ventricular pacing may be provided using a coronary sinus lead, resulting in Left Bundle Branch Area Pacing Optimized Cardiac Resynchronization Therapy (LOT-CRT). The intervention aims to achieve more physiological ventricular activation than conventional biventricular pacing, improve electrical synchrony, promote reverse ventricular remodeling, and reduce heart failure-related adverse events.
Also known as: Cardiac resynchronization therapy using left bundle branch area pacing with or without LV lead optimization., Cardiac resynchronization guided by conduction system pacing to improve ventricular synchrony.
Composite of All-Cause Mortality and Heart Failure Hospitalization
Time to first occurrence of the composite endpoint of all-cause mortality or hospitalization due to worsening heart failure during the 24-month follow-up period.
Time frame: 24 months
Change in Left Ventricular Ejection Fraction (LVEF)
Change in left ventricular ejection fraction measured by transthoracic echocardiography between baseline and 24-month follow-up. Ejection fraction is measured in percentage (%). Improvement in ejection fraction is detected as increase in percentage-value.
Time frame: Baseline to 24 months
Change in Left Ventricular End-Systolic Volume ( LV ESV)
Change in left ventricular end-systolic volumen measured by echocardiography between baseline and 24-month follow-up. Left ventricular end-systolic volume in measured in mililiters ( ml) , decrease in LV ESV is a sign of clinical response on therapy.
Time frame: Baseline to 24 months
Change in paced QRS Duration
Reduction in QRS duration following cardiac resynchronization therapy compared with baseline electrocardiographic measurements. Paced QRS duration is measured in miliseconds (ms). Decrease in paced QRS duration compared to preoperative QRS duration is marked as a good signal in cardiac resynchronization therapy.
Time frame: Baseline to 24 months
New York Heart Association Heart Failure Functional Status
Change in New York Heart Association (NYHA) functional class from baseline to follow-up. Stage I-IV. NYHA improvement is detected as decrease in NYHA stage grade.
Time frame: Baseline to 24 months
Device-Related and Procedure-Related Complications
Incidence of device-related and procedure-related adverse events, including lead dislodgement, infection, pneumothorax, pocket hematoma, and system revision.
Time frame: 24 months
Plan to share: Undecided — ndividual participant data will be shared only in a de-identified form and in accordance with applicable data protection regulations, institutional policies, and informed consent provisions. Data sharing may be limited where participant privacy, ethical considerations, or legal requirements prevent full disclosure of individual-level data.
This study is not yet recruiting, as verified in Jul 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.