Early Improvement in 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 prospective descriptive single‐center study. We analyzed patients who develop LVDys with n‐PS, and the results after upgrading to conduction system pacing (CSP). Ultra‐high frequency electrocardiogram (UHF‐ECG) was performed pre and post‐implantation of the last patients included. ECG recordings in 16 frequency bands (150–1000 Hz) 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–V6 (electrical dyssynchrony [DYS‐e] 16) and V1–V8 (DYS‐e 18) defined ventricular dyssynchrony. Data were expressed as mean ± standard deviation. Results 27 patients were upgraded 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 10 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. The last eight patients included were studied in terms of ventricular synchrony parameters by UHF‐ECG (VDI Technologies), both His bundle pacing (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 underdiagnosed. UHF‐ECG provides useful new information about ventricular activation and will likely improve patient selection for cardiac resynchronization therapy (CRT).