Curila K, Prochazkova R, Jurak P, et al. - In this study including 46 patients with His bundle pacing to manage bradycardia and spontaneous QRSs without a bundle branch block, researchers analyzed ultra-high-frequency ECG (UHF-ECG) depolarization patterns during myocardial and His bundle pacing. They performed UHF-ECG recordings during spontaneous rhythm, pure myocardial para-Hisian, and His bundle capture. They calculated QRS duration, QRS area, depolarization time under particular leads, and the UHF-ECG derived ventricular dyssynchrony index. Findings revealed that both types of His bundle, but not myocardial, capture resulted in the preservation of ventricular electrical synchrony as measured using UHF-ECG in patients without bundle branch block.