The Role of Paced QRS Morphology in Determining Initial Site for Lead Placement in Left Bundle Branch Area Pacing

Determining proper initial site on the right side of interventricular septum is the first step to implant LBBAP lead. Electrocardiographic features such as discordance of paced QRS polarity in leads II and III (alternatively in aVL and aVR) and the presence of notch in lead V1 are in use but have not yet been evaluated. This study aimed to establish the role of paced QRS morphology in determining the initial site for LBBAP lead deployment.

A group of 150 LBBAP device implantations containing 327 lead placement attempts were analyzed. Final electrocardiographic results of LBBAP and the success rate of lead deployment attempts were evaluated depending on paced QRS complex features at the initial site of lead placement.

Final electrocardiographic outcomes of LBBAP (paced QRS duration, R-wave peak time in V6, prevalence of confirmed LBB capture) were independent of leads II and III dominant polarity combination (both negative vs. discordant vs. both positive). Lead deployment success rate was the highest in area with negative QRS in leads II and III (OR 2.99, p < 0.001). Notched QRS in V1 was also the predictor of successful lead placement (OR 1.95, p = 0.005). The 95.7% of screwings were attempted in area characterized by aVL and aVR discordance. No coronary complications were noted. LVEF was stable.

Wide area of interventricular septum may be used for LBBAP with similar electrocardiographic outcome and aVL/aVR discordance may delineate a safe target zone. LBBAP lead implantation is probably the easiest in the inferior part of septum.