Early improvement on cardiac function and dyssynchrony after physiological upgrading in pacing-induced cardiomyopathy

Abstract Background Interventricular dyssynchrony derived from the classic non-physiological stimulation (n-PS) of the right ventricle (RV) is a known cause of left ventricular dysfunction (LVDys). Methods This was a retrospective descriptive single-center study. We analyzed patients who develop LVDys with n-PS, and the results after upgrading to conduction system pacing (CSP). UHF-ECG was performed pre and post implantation of the last patients included. ECG recordings in 16 frequency bands (150-1000Hz) were used to create maps of ventricular depolarization. The maximum time difference between the centers of mass of the complex UHF QRS of leads V1 to V6 (DYS-e 16) and V1 to V8 (DYS-e 18) defined ventricular dyssynchrony. Data were expressed as mean +- standard deviation. Results 27 patients were up-graded to CSP from January/2022 to January/2024 after developing LVDys. Permanent His Bundle pacing (p-HBP) was achieved in 63% (n=17); in the other ten patients left bundle branch area pacing (LBBAp) was performed. The average baseline LVEF improved from 34,5% (27-42) to 47,6% (38.2-57), p<0.001. Telediastolic left ventricle diameter as well as QRS width also decreased. Thresholds remained stable at 6-month follow up. Last eight patients included were studied in terms of ventricular synchrony parameters by UHF-ECG (VDI Technologies), both HBP and the LBBAp achieved significant improvement with respect to baseline parameters. Conclusions LVEF improved in patients with previous n-PS induced cardiomyopathy after upgrading to CSP. LVDys due to dyssynchronopathy is frequent and probably under-diagnosed. UHF-ECG provides useful new information about ventricular activation and will likely improve patient selection for CRT.