Abstract 16153: Electrocardiographic Correlations With Cardiac Magnetic Resonance in Left Bundle Branch Area Pacing

Abstract

Introduction: As the use of left bundle branch area pacing (LBBAP) continues to increase, there remains uncertainty about the mechanical effects of achieving selective LBB capture. Hypothesis: The hypothesis was that cardiac magnetic resonance (CMR) strain and functional parameters would be similar with and without LBBAP, and mechanical function would be more favorable with surface ECG parameters indicative of LBB capture. Methods: CMR was performed at 3T in two centers in the first year after implantation of dual-chamber pacemakers with LBBAP. Imaging sets were obtained with dual-chamber LBBAP (DOO mode) and, in patients with intact atrioventricular (A-V) conduction, atrial-only pacing (AOO mode), including strain imaging with displacement encoding with stimulated echoes (DENSE). Results: In 17 patients, the median LVEF with LBBAP was 50% (IQR 48-52%). The median LVEF and RVEF were similar with LBBAP on (DOO mode) and off (AOO mode) (p=0.27 and p=0.37, respectively); however, there were differences in synchrony (CURE-SVD) (p=0.0081), mean septal Ecc (p=0.011), and mean LV free wall Ecc (p=0.011) that favored atrial-only pacing with A-V conduction vs. sequential LBBAP (Figure 1). A shorter interval between R wave peaks in ECG leads V6 and V1 (V6-V1 interpeak interval), shown to be associated with selective LBB capture, was the best predictor of a greater LVEF with LBBAP (p=0.0016). A shorter paced QRS duration predicted greater global Ecc (p=0.044) and more synchrony by the CURE-SVD (p=0.027) (Figure 2). Conclusions: LBBAP reproduces biventricular function by CMR with some differences noted in CMR strain, and selective LBB capture was associated with a greater LVEF by CMR.