Both Selective and Non-Selective His Bundle, but not Myocardial, Pacing Preserve Ventricular Electrical Synchrony Assessed by Ultra-High-Frequency ECG

Abstract Background Right ventricular myocardial pacing leads to non-physiological activation of heart ventricles. Contrary to this, His bundle pacing preserves their fast activation. Ultra-high-frequency ECG (UHF-ECG) is a novel tool for ventricular depolarization assessment. Objective To describe UHF-ECG depolarization patterns during myocardial and His bundle pacing. Methods Forty-six patients with His bundle pacing to treat bradycardia and spontaneous QRSs without a bundle branch block were included. UHF-ECG recordings were performed during spontaneous rhythm, pure myocardial para-Hisian, and His bundle capture. QRS duration, QRS area, depolarization time under specific leads, and the UHF-ECG derived ventricular dyssynchrony index were calculated. Results One hundred and thirty-three UHF-ECG recordings were performed in 46 patients (44 spontaneous, 28 selective, 43 non-selective His bundle, and 18 myocardial captures). The mean QRS duration was 117 ms for spontaneous, 118 ms for selective, 135 ms for non-selective, and 166 ms for myocardial capture (p Conclusion In patients without bundle branch block, both types of His bundle, but not myocardial, capture preserve ventricular electrical synchrony as measured using UHF-ECG.