Resynchronization TherapyCONSYST-CRTNCT05187611
Conduction System Pacing vs Biventricular Resynchronization Therapy in Systolic Dysfunction and Wide QRS: CONSYST-CRT.
A study testing Conduction system pacing and Biventricular pacing in people with Resynchronization Therapy and Conduction System Pacing, run by Hospital Clinic of Barcelona at 1 site in Spain.
Trial summary
Conduction system pacing vs biventricular resynchronization therapy in systolic dysfunction and wide QRS (CONSYST-CRT randomized clinical trial) is a non-inferiority trial that aims to study the composite endpoint consisting of all-cause mortality, cardiac transplant, heart failure hospitalizations, and left… Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Resynchronization Therapy, Conduction System Pacing
- What is being tested?
- Conduction system pacing and Biventricular pacing
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 130 participants
- Where
- 1 siteSpain
- Study dates
- 17 Jan 2022to 1 Apr 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- The patient must indicate their acceptance to participate in the study by signing an informed consent document.
- The patient must be ≥ 18 years of age.
- Left bundle branch block, QRS ≥130 and LVEF <=35%. No indication of stimulation for AV block.
- Non-left bundle branch block, QRS ≥150 and LVEF <=35%.
- Patients with indication of resynchronization therapy for ventricular dysfunction (LVEF <40%) and indication of cardiac pacing for AV block.
- LVEF <=35% in NYHA class III or IV if they are in atrial fibrillation and have intrinsic QRS >=130 ms, provided a strategy to ensure biventricular capture is in place.
Who cannot join
- Myocardial infarction, unstable angina or cardiac revascularization during the previous 3 months.
- Pregnancy.
- Participating currently in a clinical investigation that includes an active treatment.
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Conduction System Pacing vs Biventricular Resynchronization Therapy in Systolic Dysfunction and Wide QRS: CONSYST-CRT Randomized Clinical Trial.
Conduction system pacing vs biventricular resynchronization therapy in systolic dysfunction and wide QRS (CONSYST-CRT randomized clinical trial) is a non-inferiority trial that aims to study the composite endpoint consisting of all-cause mortality, cardiac transplant, heart failure hospitalizations, and left ventricular ejection fraction (LVEF) improvement <5 points.
Read the detailed description
To date, studies have shown that conduction system pacing could get similar clinical and echocardiographic responses to those obtained with biventricular therapy.
This study will randomize 130 patients to a strategy of biventricular pacing versus conduction system pacing.
CONSYST-CRT study will analyze the following parameters in the 2 groups: left ventricular ejection fraction, ventricular volumes, echocardiographic response (>=15% decrease in left ventricular end-systolic volume), NYHA functional class, heart failure hospitalization, all-cause mortality, cardiac transplant, QRS shortening, echocardiographic asynchrony (septal flash).
Clinical, electrocardiographic, echocardiographic follow-up will be performed for 1 year.
The first 70 patients have been recruited in the context of the LEVELAT study (ClinicalTrials.gov Identifier: NCT04054895)
- Being tested
- Conduction system pacing, Biventricular pacing
- Keywords
- Resynchronization Therapy, Biventricular pacing, Conduction system pacing
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Conduction system pacingDevice
Lead placed in the His-Purkinje system in order to achieve QRS shortening.
Biventricular pacingDevice
Lead is placed in a tributary of the coronary sinus.
| Study group | Role | What they receive |
|---|---|---|
| Conduction system pacing | Experimental | Pacing the His-Purkinje system.
Crossover to biventricular pacing was allowed in case of failed conduction system pacing: failed His bundle pacing and failed Left bundle branch pacing (high thresholds (>3.5V / 1ms); no left bundle branch pacing criteria; no left bundle branch correction).
Electrocardiographic optimization allowed in order to obtain the narrowest QRS. Receives: Device: Conduction system pacing |
| Biventricular pacing | Active comparator | Pacing from the right ventricular and coronary sinus leads. Electrocardiographic optimization with fusion-optimized intervals.
Crossover from biventricular pacing to conduction system pacing will be allowed in the following situations: coronary sinus cannot be cannulated; no lateral or posterolateral branches; or phrenic stimulation. Receives: Device: Biventricular pacing |
What is being measured
The primary outcome is the main question the study is designed to answer.
Composite end-point: all-cause mortality, cardiac transplant, heart failure hospitalization, and left ventricular ejection fraction (LVEF) improvement <5 points.
Non inferiority margin 10%.
Measured: 12 months
Secondary outcomes (7)
Change in left ventricular ejection fraction.
Non inferiority margin 2.5%
Measured: 6 months; 12 months
Change in left ventricular end-systolic volume.
Non inferiority margin 3%
Measured: 6 months; 12 months
Echocardiographic response (>=15% decrease in left ventricular end-systolic volume).
Non inferiority margin 10%
Measured: 6 months; 12 months
Hospitalization due to heart failure, mortality or cardiac transplant (combined endpoint)
Non inferiority margin 10%
Measured: 6 months; 12 months
QRS shortening
Non inferiority margin 12ms
Measured: Post-implantation (Electrophysiology Lab)
Correction of septal flash
Non inferiority margin 0.5mm
Measured: 15 days; 6 months; 12 months
Change in NYHA functional class
NYHA functional class I, II, III, IV.
Measured: 6 months; 12 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted12 Jan 2022
- Study start17 Jan 2022
- Primary completion15 Jul 2024
- Study completion1 Apr 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Resynchronization TherapyStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- The first 70 patients have been recruited in the context of the LEVELAT study (ClinicalTrials.gov Identifier: NCT04054895)
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 130 participants (actual)
Sponsor and investigators
- Lead sponsor
- Hospital Clinic of Barcelona
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Josep Lluis Mont Girbau, Hospital Clinic of Barcelona
- Investigators
- Lluís Mont, MD, PhD, Study director, Hospital Clinic of BarcelonaJose M Tolosana, MD, PhD, Principal investigator, Hospital Clinic of BarcelonaMargarida Pujol Lopez, MD, Principal investigator, Hospital Clinic of Barcelona
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05187611
- Sponsor's protocol ID
- CONSYST-CRT.
- Acronym
- CONSYST-CRT
- Status last verified
- Jul 2025
- First submitted
- 19 Dec 2021
- Last updated
- 10 Jul 2025
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- Yes
Publications
Pujol-Lopez M, Graterol FR, Borras R, Garcia-Ribas C, Guichard JB, Regany-Closa M, Jimenez-Arjona R, Niebla M, Poza M, Carro E, Castel MA, Arbelo E, Porta-Sanchez A, Sitges M, Roca-Luque I, Doltra A, Guasch E, Tolosana JM, Mont L. Clinical Response to Resynchronization Therapy: Conduction System Pacing vs Biventricular Pacing: The CONSYST-CRT Trial. JACC Clin Electrophysiol. 2025 Aug;11(8):1820-1831. doi: 10.1016/j.jacep.2025.03.024. Epub 2025 May 14.
PubMed 40372330
Study at a glance
From the registry record, last updated by the sponsor on 10 Jul 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Conduction System Pacing vs Biventricular Resynchronization Therapy in Systolic Dysfunction and Wide QRS: CONSYST-CRT Randomized Clinical Trial.
- ClinicalTrials.gov ID
- NCT05187611
- Acronym / sponsor ID
- CONSYST-CRT / CONSYST-CRT.
- Keywords
- Resynchronization Therapy, Biventricular pacing, Conduction system pacing
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 130 participants (actual)
- Lead sponsor
- Hospital Clinic of BarcelonaUniversity, hospital or other
- Study start
- 17 Jan 2022 (actual)
- Primary completion
- 15 Jul 2024 (actual)
- Study completion
- 1 Apr 2025 (actual)
- First posted
- 12 Jan 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Conduction system pacing vs biventricular resynchronization therapy in systolic dysfunction and wide QRS (CONSYST-CRT randomized clinical trial) is a non-inferiority trial that aims to study the composite endpoint consisting of all-cause mortality, cardiac transplant, heart failure hospitalizations, and left ventricular ejection fraction (LVEF) improvement <5 points.
Detailed description
To date, studies have shown that conduction system pacing could get similar clinical and echocardiographic responses to those obtained with biventricular therapy.
This study will randomize 130 patients to a strategy of biventricular pacing versus conduction system pacing.
CONSYST-CRT study will analyze the following parameters in the 2 groups: left ventricular ejection fraction, ventricular volumes, echocardiographic response (>=15% decrease in left ventricular end-systolic volume), NYHA functional class, heart failure hospitalization, all-cause mortality, cardiac transplant, QRS shortening, echocardiographic asynchrony (septal flash).
Clinical, electrocardiographic, echocardiographic follow-up will be performed for 1 year.
The first 70 patients have been recruited in the context of the LEVELAT study (ClinicalTrials.gov Identifier: NCT04054895)
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (participant)
- Number of arms
- 2
- Model description
- The first 70 patients have been recruited in the context of the LEVELAT study (ClinicalTrials.gov Identifier: NCT04054895)
| Arm | Type | Receives |
|---|---|---|
| Conduction system pacing | Experimental | Device: Conduction system pacingPacing the His-Purkinje system. Crossover to biventricular pacing was allowed in case of failed conduction system pacing: failed His bundle pacing and failed Left bundle branch pacing (high thresholds (>3.5V / 1ms); no left bundle branch pacing criteria; no left bundle branch correction). Electrocardiographic optimization allowed in order to obtain the narrowest QRS. |
| Biventricular pacing | Active comparator | Device: Biventricular pacingPacing from the right ventricular and coronary sinus leads. Electrocardiographic optimization with fusion-optimized intervals. Crossover from biventricular pacing to conduction system pacing will be allowed in the following situations: coronary sinus cannot be cannulated; no lateral or posterolateral branches; or phrenic stimulation. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (6 listed)
- The patient must indicate their acceptance to participate in the study by signing an informed consent document.
- The patient must be ≥ 18 years of age.
- Left bundle branch block, QRS ≥130 and LVEF <=35%. No indication of stimulation for AV block.
- Non-left bundle branch block, QRS ≥150 and LVEF <=35%.
- Patients with indication of resynchronization therapy for ventricular dysfunction (LVEF <40%) and indication of cardiac pacing for AV block.
Key exclusion criteria (3 listed)
- Myocardial infarction, unstable angina or cardiac revascularization during the previous 3 months.
- Pregnancy.
- Participating currently in a clinical investigation that includes an active treatment.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Conduction system pacingLead placed in the His-Purkinje system in order to achieve QRS shortening. | Device | Conduction system pacing |
| Biventricular pacingLead is placed in a tributary of the coronary sinus. | Device | Biventricular pacing |
Primary outcome
Composite end-point: all-cause mortality, cardiac transplant, heart failure hospitalization, and left ventricular ejection fraction (LVEF) improvement <5 points.
Time frame: 12 months
Non inferiority margin 10%.
7 secondary outcomes
Change in left ventricular ejection fraction.
Time frame: 6 months; 12 months
Change in left ventricular end-systolic volume.
Time frame: 6 months; 12 months
Echocardiographic response (>=15% decrease in left ventricular end-systolic volume).
Time frame: 6 months; 12 months
Hospitalization due to heart failure, mortality or cardiac transplant (combined endpoint)
Time frame: 6 months; 12 months
QRS shortening
Time frame: Post-implantation (Electrophysiology Lab)
Correction of septal flash
Time frame: 15 days; 6 months; 12 months
Change in NYHA functional class
Time frame: 6 months; 12 months
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 10 Jul 2025.
- Derived from this study: PubMed 40372330Pujol-Lopez M, Graterol FR, Borras R, Garcia-Ribas C, Guichard JB, Regany-Closa M, Jimenez-Arjona R, Niebla M, Poza M, Carro E, Castel MA, Arbelo E, Porta-Sanchez A, Sitges M, Roca-Luque I, Doltra A, Guasch E, Tolosana JM, Mont L. Clinical Response to Resynchronization Therapy: Conduction System Pacing vs Biventricular Pacing: The CONSYST-CRT Trial. JACC Clin Electrophysiol. 2025 Aug;11(8):1820-1831. doi: 10.1016/j.jacep.2025.03.024. Epub 2025 May 14.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Lluís Mont, MD, PhD study director
Hospital Clinic of Barcelona
Jose M Tolosana, MD, PhD principal investigator
Hospital Clinic of Barcelona
Margarida Pujol Lopez, MD principal investigator
Hospital Clinic of Barcelona
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Conduction system pacing and Biventricular pacing in people with Resynchronization Therapy and Conduction System Pacing, run by Hospital Clinic of Barcelona at 1 site in Spain.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 6 inclusion and 3 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 10 Jul 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Spain. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Composite end-point: all-cause mortality, cardiac transplant, heart failure hospitalization, and left ventricular ejection fraction (LVEF) improvement <5 points. (time frame: 12 months). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05187611, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 10 Jul 2025.