Is the pacing site closer to the left ventricular septal endocardium in left bundle branch pacing or in left ventricular septal pacing?

Purpose: Distinguishing between left bundle branch pacing (LBBP) and left ventricular septal pacing (LVSP) is challenging. This study aimed to compare the echocardiographic distance from the pacing lead tip to the left ventricular (LV) septal endocardium between patients who underwent LBBP and those who underwent LVSP successfully.

Methods: Fifty-nine consecutive patients (age 71.