Narrow QRS ectopy with concealed connections from a para‐Hisian origin to the proximal left fascicles

Introduction Catheter ablation of ectopy originating from the vicinity of the His bundle can be challenging. Methods and Results We report a case of a 33‐year‐old man with narrow QRS ectopy with preferential conduction from a para‐Hisian origin to the proximal left fascicles, which was successfully eliminated by radiofrequency ablation in the right coronary cusp, guided by ultrahigh‐resolution mapping of the His bundle, bundle branch, and fascicular electrograms. Conclusion Some narrow QRS ectopy may originate from the vicinity of the conduction system, instead of the “true” conduction system, and have concealed connections from its origin to the conduction system.