Conduction System Pacing vs Biventricular Pacing in Systolic Dysfunction and Wide QRS: Mortality, Heart Failure Hospitalization or Cardiac Transplant (CONSYST-CRT II)

Conduction System Pacing vs Biventricular Resynchronization Therapy in Systolic Dysfunction and Wide QRS: Mortality, Heart Failure Hospitalization or Cardiac Transplant

Conduction system pacing vs biventricular resynchronization therapy in systolic dysfunction and wide QRS: mortality, heart failure hospitalization or cardiac transplant (CONSYST-CRT II trial).

Superiority trial that aims to study the composite endpoint consisting of all-cause mortality, cardiac transplant or heart failure hospitalization at 12-month follow-up.

Study Overview

• Status: Recruiting
• Conditions: Heart Failure; Cardiac Resynchronization Therapy
• Intervention / Treatment: Procedure: Conduction system pacing; Procedure: Biventricular pacing

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 320 patients to a strategy of biventricular pacing versus conduction system pacing.

CONSYST-CRT II study will analyze a clinical endpoint as primary endpoint and the following parameters in both 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 dyssynchrony (atrioventricular, interventricular, intraventricular) and global longitudinal strain.

As a secondary endpoint, baseline predictors of response to conduction system pacing and biventricular pacing according to cardiac magnetic ressonance and electrocardiographic imaging will be studied.

Clinical, electrocardiographic, echocardiographic follow-up will be performed during 12 months.

• Study Type: Interventional
• Enrollment (Estimated): 320
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Jose Mª Tolosana, MD, PhD; Phone Number: 93 2271778 (2094); Email: tolosana@clinic.cat
• Study Contact Backup: Name: Margarida Pujol López, MD; Phone Number: 93 2271778 (2094); Email: mapujol@clinic.cat

Study Locations

• Spain
  • Barcelona, Spain
    • Recruiting
    • Hospital Clinic De Barcelona
    • Contact: JM Tolosana, MD, PhD; Email: tolosana@clinic.cat
    • Contact: M Pujol Lopez, MD

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Patient must indicate acceptance to participate in the study by signing an informed consent document.
• 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%.
• Resynchronization therapy indication for ventricular dysfunction (LVEF <40%) and indication of cardiac pacing for AV block.
• LVEF <=35% in NYHA class III or IV, atrial fibrillation and intrinsic QRS >=130 ms, provided a strategy to ensure biventricular capture is in place.

Exclusion Criteria:

• Myocardial infarction, unstable angina or cardiac revascularization during the previous 3 months.
• Pregnancy.
• Participating currently in a clinical investigation that includes an active treatment.

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: Conduction system pacing; Pacing the His-Purkinje system. Crossover to biventricular pacing 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.	Procedure: Conduction system pacing; Conduction system pacing implant as a Resynchronization therapy.
Active Comparator: Biventricular pacing; Pacing from the right ventricular and coronary sinus lead. Electrocardiographic optimization with fusion-optimized intervals (FOI). 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.	Procedure: Biventricular pacing; Biventricular pacing implant

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Composite end-point: all-cause mortality, cardiac transplant or heart failure hospitalization.	Clinical follow-up at 12 months	1 year

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in left ventricular ejection fraction.	Left ventricular ejection fraction measured with Simpson method with echocardiography.	6 months; 1 year
Change in left ventricular end-systolic volume.	Left ventricular volumes measured with echocardiography. Simpson rule from 2- and 4-chamber apical views.	6 months; 1 year
Echocardiographic response.	>=15% decrease in left ventricular end-systolic volume	6 months; 1 year
Change in NYHA functional class.	NYHA functional class I, II, III, or IV	6 months; 1 year
QRS shortening.	QRS duration (milliseconds). QRS onset measured from fast deflection and from spike.	Immediately after the intervention
Correction of septal flash.	Fast inward-outward movement of the interventricular septum in early systole. Using M-mode in parasternal short and long-axis views, septal flash was quantified (in millimeters) as the highest amplitude of the early inward motion measured from the resting position prior to the onset of septal contraction. The pair of septal flash measures (baseline and final) was obtained at the axis with the highest baseline SF.	15 days; 6 months; 1 year
Correction of auriculoventricular dyssynchrony.	Left ventricular filling time. The left ventricular filling time was measured from the onset of the E-wave to the end of the A-wave, and the R-R interval was measured to calculate the percentage of filling time relative to the cardiac cycle (LV filling time/RR, %).	15 days; 6 months; 1 year
Correction of interventricular dyssynchrony.	Quantified using pulsed Doppler and calculated as the time difference between QRS onset and the onset of the flow wave in the right and left outflow tracts.	15 days; 6 months; 1 year
Change in global longitudinal strain (GLS).	Strain myocardial deformation of the left ventricle was quantified offline from 2-dimensional echocardiography using speckle tracking (2Dstrain, Echo Pac, version 202.41.0, GE Healthcare Milwaukee, WI). The long-axis cine images (2-, 3-, and 4-chamber views), were used to determine GLS.	15 days; 6 months; 1 year
Description of baseline predictors of response to conduction system pacing and biventricular pacing. Cardiac fibrosis quantification.	Cardiac fibrosis quantification (grams of fibrosis)	Baseline (pre intervention).
Description of baseline predictors of response to conduction system pacing and biventricular pacing with Electrocardiographic Imaging. Left ventricular activation time (LVAT), ms.	Left ventricular activation time (LVAT), ms.	Baseline (pre intervention). And immediately after the intervention
Description of baseline predictors of response to conduction system pacing and biventricular pacing with Electrocardiographic Imaging. Ventricular electrical uncoupling (VEU).	Ventricular electrical uncoupling (VEU) = mean left ventricular activation time - mean right ventricular activation time, ms	Baseline (pre intervention). And immediately after the intervention
Description of baseline predictors of response to conduction system pacing and biventricular pacing with Electrocardiographic Imaging. Left ventricular dyssynchrony index (LVDI).	Left ventricular dyssynchrony index (LVDI): standard deviation of individual activations recorded from the left ventricle.	Baseline (pre intervention). And immediately after the intervention
Description of baseline predictors of response to conduction system pacing and biventricular pacing with Electrocardiographic Imaging. Conduction velocity (cm/s).	Conduction velocity (cm/s).	Baseline (pre intervention). And immediately after the intervention

Collaborators and Investigators

• Sponsor: Hospital Clinic of Barcelona
• Collaborators: Institut d'Investigacions Biomèdiques August Pi i Sunyer
• Investigators: Principal Investigator: José Mª Tolosana, MD, PhD, Hospital Clínic de Barcelona. Institut d'Investigacions Biomèdiques August Pi i Sunyer; Principal Investigator: Margarida Pujol López, MD, Hospital Clínic de Barcelona. Institut d'Investigacions Biomèdiques August Pi i Sunyer; Study Chair: Lluís Mont, MD, PhD, Hospital Clínic de Barcelona. Institut d'Investigacions Biomèdiques August Pi i Sunyer

Study record dates

Study Major Dates

• Study Start (Actual): November 27, 2023
• Primary Completion (Estimated): November 1, 2027
• Study Completion (Estimated): January 1, 2028

Study Registration Dates

• First Submitted: October 4, 2023
• First Submitted That Met QC Criteria: October 26, 2023
• First Posted (Actual): October 27, 2023

Study Record Updates

• Last Update Posted (Actual): April 3, 2026
• Last Update Submitted That Met QC Criteria: March 30, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: cardiac resynchronization therapy; left bundle branch pacing; biventricular pacing
• Additional Relevant MeSH Terms: Cardiovascular Diseases; Heart Diseases; Heart Failure; Therapeutics; Electric Stimulation Therapy; Cardiac Pacing, Artificial; Cardiac Resynchronization Therapy
• Other Study ID Numbers: CONSYST-CRT II

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No