Invasive assessment of right ventricular activation patterns with left bundle branch area pacing (LBBAP) and left bundle optimized cardiac resynchronization therapy (LOT-CRT)

Background Left bundle branch area pacing (LBBAP) and left bundle optimized cardiac resynchronization therapy (LOT-CRT) are both used to achieve LV resynchronization. The effects of these two modalities on RV activation is unclear.. We assessed RV activation patterns between right-sided LBBAP (R-LBBAP), left-sided LBBAP (L-LBBAP) and LOT-CRT using invasive electroanatomic mapping. Methods Eight patients underwent invasive electroanatomical mapping of the right ventricle at baseline, during right-sided LBBAP (R-LBBAP), left-sided LBBAP (L-LBBAP) and LOT-CRT, respectively. Temporary LOT-CRT was performed using a an intracardiac catheter placed on the endocardial left ventricular lateral wall and the implanted left bundle lead. Temporary L-LBBAP was performed using an intracardiac catheter placed on the left ventricular septum to achieve left bundle capture. Results Right ventricular activation patterns differed according to the type of stimulation. Right ventricular breakthrough activation site was predominantly high septal for LBBAP (6/8) and L-LBBAP (6/8), while LOT-CRT produced equal numbers of high septal (3/6) and mid septal (3/6) activation. Conclusion Both left and right sided LBBAP produced comparable patterns of right ventricular activation whereas LOT-CRT resulted in a differing pattern of RV activation that may have consequences to right ventricular synchrony and function.