Dyssynchrony assessment by ultra-high-frequency electrocardiography: a single numerical parameter to identify the relationship between right and left ventricular depolarization

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): grant number NU21-02-00584, the CAS project RVO:68081731, the project National Institute for Research of Metabolic and Cardiovascular Diseases (Programme EXCELES, ID Project No. LX22NPO5104) - Funded by the European Union – Next Generation EU. Background The common criterion for assessing synchronous activation during single and biventricular pacing is QRS duration (QRSd). The novel conduction system pacing (CSP) techniques provide more physiological ventricular activation but less clear effects on QRSd. In these circumstances, a more detailed and visual assessment of ventricular synchrony than QRSd alone can be insightful. Purpose To investigate whether differences between various modes of CSP can be better differentiated by ultra-high-frequency ECG (UHF-ECG) than by QRSd. Methods UHF-ECG recordings were acquired in 199 bradycardia patients with narrow QRS complex during intrinsic rhythm, selective (sHBP) and non-selective His bundle (nHBP), selective (sLBBP) and non-selective left bundle branch (nsLBBP) pacing, and left (LVSP) and right ventricular septal pacing (RVSP). Lead positions were certified using X-ray and QRS morphology. Electrical dyssynchrony (e-DYS) was calculated from UHF-ECG activation times as the maximal time difference between the peaks of ECG leads V1-V6. Positive e-DYS indicates delayed left ventricular (LV) activation, whereas negative e-DYS means delayed right ventricular (RV) activation. Results The Figure shows the relationship between QRSd and e-DYS for individual types of stimulation on an intrinsic background (black). All pacing, except sHBP, modes significantly increased QRSd. QRSd was significantly larger during RVSP than all other pacing modes, but QRSd was not able to differentiate between nsHBP, sLBBP, nsLBBP and LVsp. In contrast to QRSd, e-DYS was positive during nsHBP and RVSP and negative during sLBBP, nsLBBP and LVSP (p<0.001). Conclusion e-DYS assessed with UHF-ECG provides more detailed information on the ventricular activation and is more superior in differentiating between CSP pacing modes, compared to standard QRSd. sHBP, nsHBP, nsLBBp, and LVSP create activation patterns closest to normal ventricular activation.