LBBP + CSP Versus LBBP Alone for Cardiac Resynchronization Therapy (LOTTO-CRT)

June 17, 2026 updated by: Clinica Cardio VID

Left Bundle Branch Pacing + Coronary Sinus Pacing Versus Left Bundle Branch Pacing Alone for Cardiac Resynchronization Therapy in Patients Eligible for CRT-P A Randomized Crossover Pilot Clinical Trial

The purpose of this pilot clinical trial is to evaluate whether a novel cardiac resynchronization strategy, called LOT-CRT, is more effective than standard physiological pacing alone (LBBAP) in patients with heart failure.

This is a randomized, single-center, crossover pilot study involving 10 patients. All participants will receive a specialized pacemaker (CRT-P) with leads implanted in two specific areas: the Left Bundle Branch Area (LBBAP) and the Coronary Sinus (CS).

Because of the crossover design, each patient will serve as their own control, receiving two different pacing configurations in a random order: Active Phase (LOT-CRT): Simultaneous pacing of the left bundle branch and the coronary sinus. Control Phase (LBBAP alone): Pacing only the left bundle branch area. Each treatment phase will last 6 months, for a total follow-up of 12 months per patient.

By testing both strategies in the same patient, this study will help clinicians identify the most effective way to restore heart synchrony and improve clinical outcomes in patients with advanced heart failure and conduction delays.

Study Overview

Status

Active, not recruiting

Conditions

Intervention / Treatment

Detailed Description

This is a single-center, randomized, crossover pilot clinical trial. Each patient will serve as their own control. Following the successful implantation of a device capable of stimulating the LBBAP and the coronary sinus, participants will be randomly assigned to one of two treatment sequences:

Sequence A: LOT-CRT (LBBAP + CS) for 6 months, followed by LBBAP alone Sequence B: LBBAP alone for 6 months, followed by LOT-CRT Each treatment phase will last 6 months, followed by an end-point evaluation and a crossover. Since the hemodynamic effect of electrical stimulation is immediate, no washout period is required between phases.

This study was designed as an exploratory pilot study; therefore, no formal sample size calculation was performed. The number of patients enrolled is considered adequate to assess the feasibility of the procedure, the safety of the crossover design, and to identify preliminary signals of clinical and electrical efficacy.

Study Type

Interventional

Enrollment (Actual)

10

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Colombia
    • Antioquia
      • Medellín, Antioquia, Colombia, 050036
        • Clinica CardioVID

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. Age ≥18 years
  2. Standard CRT-P indications according to ESC 2021 (EF ≤50%, QRS ≥130 ms, sinus rhythm or controlled AF)
  3. NYHA class II-IV
  4. Coronary venous anatomy suitable for placement of a coronary sinus electrode.
  5. Signed informed consent.
  6. Successful implantation of electrodes in the coronary sinus and in the left bundle branch area (LBBAP)

Exclusion Criteria:

  1. Concomitant indication for implantation of an implantable cardioverter-defibrillator (ICD) or CRT-D
  2. Significant uncorrected valvular disease or scheduled or anticipated cardiac surgery during the study period.
  3. Anatomical or technical contraindication for lead implantation in the coronary sinus or for lead implantation in the coronary sinus (such as sinus stenosis, coronary sinus branches unsuitable for cannulation, inability to advance and/or stabilize the lead, among others)
  4. Persistent atrial fibrillation with uncontrolled rate
  5. Comorbidities that may limit life expectancy to <1 year
  6. Participation in another clinical trial that could confound the evaluation of results within the last 6 months.
  7. Pregnancy or inadequate contraception

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: Sequence A
LOT-CRT (LBBAP + CS) for 6 months, followed by LBBAP alone
Device: Left Bundle Branch Optimized CRT

The CS lead will be implanted in a posterolateral or lateral vein using venography and standard IV delivery sheaths. Proper lead placement is confirmed by stable fixation, pacing capture, and absence of diaphragmatic pacing.

The configuration for each phase of the study (LOT-CRT or LBBAP alone) will be assigned during randomization.

Other Names:
  • LOT-CRT
  • Left bundle branch block pacing + coronary sinus pacing
  • LBBAP + CS
  • LOT-CRT Strategy
  • Combined stimulation
  • Maximized electrical resynchronization
Device: Stimulation of the left bundle branch area (LBBAP)

The LBBAP lead will be implanted via a transvenous approach using the C315His sheath, targeting the left bundle branch area in the right ventricular septum, ideally between the basal septum and the mid-septal region.

Criteria for confirming successful LBBAP capture will include:

  • Evidence of narrowing of the stimulated QRS complex compared to baseline.
  • Right bundle branch block morphology on the ECG-stimulus-to-R-wave time in V6 <80 ms (if available).
  • Low and stable pacing threshold (<1.5 V @ 0.4 ms).
  • Unipolar impedance between 400-1500 ohms. The CS lead will be implanted in a posterolateral or lateral vein using venography and standard IV delivery sheaths. Proper lead placement is confirmed by stable fixation, pacing capture, and absence of diaphragmatic pacing.
Other Names:
  • Stimulation of the left branch only
Active Comparator: Sequence B
LBBAP for 6 months only, followed by LOT-CRT
Device: Left Bundle Branch Optimized CRT

The CS lead will be implanted in a posterolateral or lateral vein using venography and standard IV delivery sheaths. Proper lead placement is confirmed by stable fixation, pacing capture, and absence of diaphragmatic pacing.

The configuration for each phase of the study (LOT-CRT or LBBAP alone) will be assigned during randomization.

Other Names:
  • LOT-CRT
  • Left bundle branch block pacing + coronary sinus pacing
  • LBBAP + CS
  • LOT-CRT Strategy
  • Combined stimulation
  • Maximized electrical resynchronization
Device: Stimulation of the left bundle branch area (LBBAP)

The LBBAP lead will be implanted via a transvenous approach using the C315His sheath, targeting the left bundle branch area in the right ventricular septum, ideally between the basal septum and the mid-septal region.

Criteria for confirming successful LBBAP capture will include:

  • Evidence of narrowing of the stimulated QRS complex compared to baseline.
  • Right bundle branch block morphology on the ECG-stimulus-to-R-wave time in V6 <80 ms (if available).
  • Low and stable pacing threshold (<1.5 V @ 0.4 ms).
  • Unipolar impedance between 400-1500 ohms. The CS lead will be implanted in a posterolateral or lateral vein using venography and standard IV delivery sheaths. Proper lead placement is confirmed by stable fixation, pacing capture, and absence of diaphragmatic pacing.
Other Names:
  • Stimulation of the left branch only

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Compare the effects of the LOT-CRT strategy versus left bundle branch block pacing (LBBAP) alone in each patient, comparing baseline to the end of the study FEVI, quality of life and functional class by NYHA.
Time Frame: 12 months
We will evaluate the following parameters in each patient: Left ventricular ejection fraction (LVEF) by echocardiography and electrocardiogram; functional capacity (NYHA class) using the 6-minute walk test and symptoms reported by the patient; quality of life (MLHFQ) using the MLHFQ quality of life scale
12 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in end-systolic diameter
Time Frame: 12 months
Absolute (mm) and relative (%) change in LVESV between baseline and 6 months.
12 months
QRS Duration
Time Frame: 12 months
Absolute (ms) and relative (%) changes in the 12-lead ECG.
12 months
Change in end-diastolic diameter
Time Frame: 12 months
Absolute (mm) and relative (%) change in LVEDV between baseline and 6 months.
12 months
NT-proBNP
Time Frame: 12 months
Absolute (ng/mL) and relative (%) change in NT-proBNP from baseline to 6 months
12 months
Echocardiographic responder
Time Frame: 12 months
LVEF ≥10% elevation or LVESV ≥15% decreased
12 months
Echocardiographic super-responder
Time Frame: 12 months
LVEF ≥50% or LVESV ≥30% decrease
12 months
Composite Clinical Outcome
Time Frame: 12 months
Cardiovascular Death or Hospitalization for Heart Failure
12 months
Procedural parameters
Time Frame: 12 months
Thresholds, P- and R-waves, impedance of each electrode.
12 months
Procedure Time/Fluoroscopy
Time Frame: 12 months
Total procedure time in minutes/ total fluoroscopy time in minutes.
12 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Clinica Cardio VID

Investigators

  • Principal Investigator: Juan F Agudelo, Electrophysiologist, Clinica CardioVID
  • Study Director: Susana Rios, Medical Epidemiologist, Clinica CardioVID

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

May 25, 2026

Primary Completion (Estimated)

July 1, 2027

Study Completion (Estimated)

December 1, 2027

Study Registration Dates

First Submitted

May 26, 2026

First Submitted That Met QC Criteria

June 17, 2026

First Posted (Actual)

June 24, 2026

Study Record Updates

Last Update Posted (Actual)

June 24, 2026

Last Update Submitted That Met QC Criteria

June 17, 2026

Last Verified

June 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • Clinica CardioVID
  • ERP -2025-14209 (Other Grant/Funding Number: Medtronic)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Individual participant data, appropriately anonymized, that support the reported results will be made available to qualified researchers for the purposes of scientific research or meta-analysis. Requests must be addressed to the Principal Investigator and include a formal proposal. All requests will be subject to approval by the institutional ethics committee. As this is a study with a small sample size (10 patients), the protocol strictly enforces confidentiality; therefore, prior approval is always required to share these data.

The data will be available from 6 months to 5 years following the publication of the main results.

IPD Sharing Time Frame

The data will be available from 6 months to 5 years following the publication of the main results.

IPD Sharing Access Criteria

Requests must be addressed to the Principal Investigator and include a formal proposal. All requests will be subject to approval by the institutional ethics committee.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • CSR

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

Yes

product manufactured in and exported from the U.S.

Yes

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Clinical Trials on Heart Failure Low Output

Clinical Trials on Left Bundle Branch Optimized CRT

Search Similar Trials

Sponsors and Collaborators

Medical Conditions

Drug Interventions

CROs by country

CROs in Nigeria

Conditions

Rare Diseases

Drug Interventions

Dietary Supplements

Sponsor/Collaborators

Locations

3
Subscribe