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

Introduction One of the challenges of left bundle branch (LBB) pacing is to place the pacing lead deep enough in the septum to obtain capture of the LBB, yet not too deep to avoid perforation. We hypothesized that the occurrence of the ectopic beats of qR/rsR’ morphology in V1 lead (fixation beats) during the lead fixation would predict that the final desired intraseptal lead depth was just reached, while the lack of fixation beats would indicate too shallow position, and 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 the fixation beats during each episode of lead rotation. We compared the presence of fixation beats during the lead rotation event directly before the LBB capture area depth was reached versus during the events before intermediate/unsuccessful positions. Results A total of 339 patients and 1278 lead rotation events were analyzed. In the retrospective phase, the fixation beats were observed in 327/339 of final lead positions and in 9/939 of intermediate lead positions (p<0.001). The sensitivity, specificity, positive and negative predictive value of the LBB area fixation beats as a marker for reaching the LBB capture area was 96.4%, 99.0%, 97.3% and 99.0%, respectively. In the prospective, fixation-beats-guided, implantation phase the fixation beats were observed in all patients and only at the LBB capture depth. Conclusions Monitoring fixation beats during deep septal lead deployment can facilitate the procedure and possibly increase the safety of lead implantation.