Cardiac resynchronization therapy risk stratified by magnetic resonance imaging and optimized by left bundle branch pacing: Results from long-term follow-up of MADURAI LBBP study.

BACKGROUND

The role of prophylactic implantable cardioverter defibrillator (ICD) in nonischemic cardiomyopathy (NICM) has been a matter of debate. Left bundle branch block-associated NICM (LB-NICM) is a progressive conduction disease, associated with excellent prognosis after left bundle branch pacing (LBBP).

OBJECTIVE

The aim of this study was to prospectively assess the long-term clinical outcomes of cardiac resynchronization therapy (CRT) risk stratified by late gadolinium enhancement cardiac magnetic resonance imaging and optimized by LBBP in patients with LB-NICM and left ventricular ejection fraction (LVEF) ≤ 35%.

METHODS

Patients with LB-NICM, LVEF ≤ 35%, and heart failure were prospectively enrolled from 2019. If scar burden was < 10% by cardiac magnetic resonance imaging, LBBP only was performed (group I), and if ≥ 10%, LBBP + ICD (group II) was performed. Primary end points were (1) composite of time to death, heart failure hospitalization, or sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) and (2) echocardiographic response (ΔLVEF ≥ 15%) at 6 months; secondary end points were (1) echocardiographic hyper-response (LVEF ≥ 50%) at 6 and 12 months and (2) need for ICD upgrade (persistent LVEF < 35% at 12 months or sustained VT or VF).

RESULTS

A total of 225 patients were enrolled after excluding 6 patients. Cardiac magnetic resonance imaging revealed < 10% scar burden in 202 patients (group I; 90%). LBBP-optimized dual-chamber pacemaker (LOT-DDD) was done in 188 patients (93%) and LOT-CRT-P in 4 patients (7%). Scar burden was ≥ 10% in 23 patients who underwent LBBP + ICD (group II). During mean follow-up of 30 ± 19 months, primary composite end point of death, heart failure hospitalization, or VT or VF occurred in 6.9% in group I vs 26.1% in group II (hazard ratio 16.52; 95% confidence interval 3.41-80.28; P = .0005). Echocardiographic response was observed in 78.2% (140/179) in group I vs 15.7% (3/19) in group II (P < .0001). Secondary end point of echocardiographic hyper-response (LVEF ≥ 50%) was observed in 64.8% vs 5.2%, 74.6% vs 25%, and 82.2% vs 25% at 6, 12, and 24 months in group I and group II, respectively. Predictors of normalization of LV function in group I include smaller LV volumes, R-wave peak time ≤ 80 ms, LVEF 30% to 35%, and absence of scar. Predictors of adverse clinical events in group I include left ventricular dimensions and presence of scar.

CONCLUSION

Cost-effective CRT may be safely provided by MAgnetic resonance imaging based DUal lead cardiac Resynchronization therapy: A prospectIve Left Bundle Branch Pacing (MADURAI LBBP) approach of risk stratifying patients with LB-NICM with late gadolinium enhancement cardiac magnetic resonance.