Postablation-acquired short atrioventricular Mahaim-type fibers: observations on their clinical, electrocardiographic, and electrophysiologic profile.

Background: The electrophysiologic characteristics of decrementally conducting accessory pathways (APs) are well described; however, little is known about decrementally conducting APs caused by the radiofrequency ablation of a rapidly conducting AP.

Objective: To report the clinical, electrocardiographic, and electrophysiologic characteristics of 6 patients who developed a decremental AP after an attempt at ablation.

Methods: We compared the clinical and electrophysiologic characteristics of 295 consecutive patients with the Wolff-Parkinson-White syndrome who underwent radiofrequency ablation of 311 manifest APs (group A) with those of 6 patients with the Wolff-Parkinson-White syndrome in whom a decrementally conducting AP was detected after an attempt at ablation.