Introduction
Premature ventricular contractions originating from the outflow tract (OT), in particular left ventricular OT (LVOT), often conduct through a preferential pathway to breakout into the global ventricular myocardium.1, 2The presence of preferential pathway conduction is mostly detected as fractionated presystolic potentials preceding the QRS onset during PVCs and late potentials during sinus rhythm (SR), and the site with those observations is considered to be an optimal site for a successful ablation.3-5 Based on these findings, a radiofrequency (RF) application to the preferential conduction is a well-developed strategy of PVC ablation, but the electrophysiologic mechanisms and significance of presystolic and late potentials during PVCs and SR at the successful ablation site have not been fully clarified. We describe a PVC case series in which the preferential pathway conduction was 3-dimensionaly visualized by coherent mapping with the conduction velocity vector. This case series might add new insight into the mechanisms of preferential pathways and PVCs.