Fixation beats: A novel marker for reaching the left bundle branch area during deep septal lead implantation

Background: One of the challenges of left bundle branch (LBB) pacing is placing the pacing lead deep enough in the septum to reach the LBB area, yet not too deep to avoid perforation.

Objective: The purpose of this study was to investigate whether the occurrence of the ectopic beats with qR/rsR' morphology in lead V₁ (fixation beats) during lead fixation would predict whether the desired intraseptal lead depth had been reached, whereas the lack of fixation beats would indicate a too-shallow position and the need for more lead rotations.

Methods: Consecutive patients during LBB pacing device implantation were analyzed retrospectively and then prospectively with respect to the occurrence of fixation beats during each episode of lead rotation. We compared the presence of fixation beats during the lead rotation event directly before the LBB area depth was reached vs during the events before intermediate/unsuccessful positions.

Results: A total of 339 patients and 1278 lead rotation events were analyzed. In the retrospective phase, fixation beats were observed in 327 of 339 final lead positions and in 9 of 939 intermediate lead positions (P <.001). Sensitivity, specificity, and positive and negative predictive values of the fixation beats as a marker for reaching the LBB area were 96.4%, 97.3%, 97.3%, and 96.5%, respectively. In the prospective, fixation beats-guided implantation phase, fixation beats were observed in all patients and only at the LBB capture depth.

Conclusion: Monitoring fixation beats during deep septal lead deployment can facilitate the procedure and possibly increase the safety of lead implantation.