Magnetic Resonance Imaging Based Risk Stratification for Defibrillator Implantation in Heart Failure Patients Requiring Cardiac Resynchronisation Therapy

Magnetic Resonance Imaging Based Risk Stratification for Defibrillator Implantation in Heart Failure Patients Requiring Cardiac Resynchronization Therapy (MADURAI CRT)

This randomized study aimed to compare the efficacy of LBBP without defibrillator vs biventricular pacing with defibrillator (BiV-ICD/CRT-D) in patients with LB-NICM and left ventricular ejection fraction (LVEF) ≤35% risk categorized by CMR imaging.

This is a single centre, prospective, randomized study in which patients with LB-NICM, LVEF ≤35% and heart failure despite guideline directed medical therapy (GDMT) will be included. CMR with gadolinium contrast will be performed to risk categorize the patient into low-risk or high risk based on presence of scar. Low risk patients (without scar ?<5%) will be randomized in 1:1 fashion to receive either LBBP without defibrillator or traditional CRT-D with biventricular pacing. LBBP will be performed by premature ventricular complex guided approach with 3830 selectsecure lead and C315His sheath in the proximal interventricular septum 1.5-2 cm distal to His bundle. LBB capture will be confirmed as per standard criteria. If LBBP lead implantation is unsuccessful, a coronary sinus lead will be placed to achieve biventricular pacing. In patients randomized to BiV-ICD, left ventricular lead will be placed in the postero-lateral branch of the coronary sinus with Q-LV duration of >90ms. If coronary sinus lead placement is unsuccessful, a LBBP lead will be implanted. The defibrillator lead will deployed in the right ventricular apical septum.

Inclusion Criteria:

1. Patients with age ≥18 years
2. Typical left bundle branch block as defined by Strauss criteria with LVEF ≤35%
3. Heart failure symptoms despite guideline directed medical therapy (GDMT)

Exclusion Criteria:

1. Patients with angiographic evidence of significant coronary artery disease requiring revascularisation. In patients with significant CAD, LVEF will be re-assessed 3 months after revascularisation to decide about CRT
2. Patients with associated uncorrected congenital or valvular heart disease
3. Expected life-expectance of <12 months due to associated comorbidities
4. Patients with contrast allergy
5. Baseline non-LBBB morphology
6. Renal dysfunction which limits the acquisition of CMR with contrast
7. Pregnant or lactating women
8. Patients who are unable to comply with study protocol