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

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.

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.