Noninvasive electrocardiographic imaging assessment of conduction system pacing device: a novel algorithm to assess intraventricular synchrony

Background. Left Bundle bracnch area pacing has become the procedure of choice for various indications including atrioventricular block and considered to be physiologic modality of pacing compare to RV apex pacing. Objectives. The purpose of this study was to assess ventricular activation and synchrony in patients with LBBAP device using ECG imaging. Methods. 25 consecutive patients underwent an LBBAP device implantation have been included in the study. ECG and ECGI analysys have been performed the day after implantation. Native and paced QRS, LVAT, RVAT and V1AD were calculated using ECG. TVACT, LVACT, LVACTi, RVACT, RVACTi and IVDS were calculated based on ECGI. All patients were followed up for at least 1 year. Results All patients were divided in 2 groups (wide and narrow QRS) based on intrinsic ECG and then based on paced ECG parameters. Study showed that for initially narrow QRS group activation time and synchrony during pacing was comparable to native. In wide QRS group these parameters were significantly improved. For paced rhythm analysis classic ECG LBBAP parameters (paced QRS and LVAT) were not sufficient to properly evaluate the ventricular activation for paced rhythm. Discordance between ECG and ECGI analysys was identified. Two additional 12 lead ECG parameters predicting the ECGI measurements were found. Follow up did not show any worsening of device parameters or Echographic and ECG signs of ventricular dissynchrony Conclusions ECG imaging can bring a significant value into assessing the efficacy of new pacing modalities and provide much more data for precise determination of implantation outcome including detailed activation assessment and comparison to intrinsic conduction. Key ECGI values confirming proper ventricular activation have been defined and corresponding 12 lead parameters were also identified.