Conduction System Pacing vs Biventricular Resynchronization Therapy in Systolic Dysfunction and Wide QRS: CONSYST-CRT.

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)

Inclusion criteria

• 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.

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.