Left Bundle Branch Area Pacing for CRT in RBBB: Results from International LBBAP Collaborative-Study Group

Abstract

Background: Cardiac resynchronization therapy (CRT) using biventricular pacing (BVP) has limited efficacy in patients with heart failure (HF) and right bundle branch block (RBBB). Left bundle branch area pacing (LBBAP) has been reported as an alternative option for BVP-CRT. The aim of the study was to assess the feasibility and outcomes of LBBAP in patients with RBBB and indication for CRT in an international, multicenter, collaborative study. Methods: LBBAP was attempted in patients with LVEF<50%, RBBB and indications for CRT. Procedural, pacing and ECG parameters, clinical response (no HF hospitalization and improvement in NYHA class) and echocardiographic response (≥5% increase in ejection fraction) to LBBAP was assessed. Results: LBBAP was attempted in 121 patients and successful in 107 (88%). Age 74±12 years, female 25%, ischemic cardiomyopathy 49%, and ejection fraction 35±9%. QRS axis at baseline was normal in 24%, left axis 63%, right axis 13%. LBBAP threshold and R-wave amplitudes were 0.8±0.3V@0.5ms and 10±9mV at implant and remained stable during mean follow-up of 13±8 months. LBBAP resulted in significant narrowing of QRS duration (156±20ms to 150±24ms (p=0.01) with R-wave peak times in V6 of 85±16ms. LVEF improved from 35±9 to 43±12%(p<0.01). Clinical and echocardiographic response was observed in 60% and 61% of patients, respectively. Female gender and reduction in QRS duration with LBBAP were predictive of echocardiographic response and super-response. Conclusions: LBBAP is a feasible and safe alternative to BVP to deliver CRT in patients with RBBB. LBBAP provides low and stable pacing thresholds with favorable clinical and echocardiographic response.