Selective His-bundle Pacing May Preserve Intrinsic Repolarization as Well as Depolarization.

A 79-year-old man with chronic atrial fibrillation underwent single-chamber His-bundle pacemaker implantation. The post-implant electrocardiogram (ECG) demonstrated selective His-bundle capture, with a narrow paced QRS and repolarization pattern similar to that of the baseline ECG. Furthermore, repolarization changes prototypic of ventricular pacing did not occur with selective His-bundle capture. While His-bundle pacing, with or without selective His-bundle capture, can preserve physiologic patterns of depolarization, only His-bundle selective pacing can preserve intrinsic ST- and T-wave patterns. Thus, the maintenance of physiologic repolarization may have various advantages, including accurate interpretation of ECG changes that are not generally interpretable in the setting of ventricular pacing.