Early Improvement in Cardiac Function and Dyssynchrony After Physiological Upgrading in Pacing-Induced Cardiomyopathy.

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).