Radiofrequency ablation of Mahaim pathway during atrial fibrillation

adiofrequency catheter ablation of accessory pathways has ecome a well-established therapy with a high rate of success. ntracardiac electrophysiologic study, mapping, and ablation of he pathway are typically performed either in sinus rhythm or uring AV reentrant tachycardia. However, atrial fibrillation ccurs commonly in these patients (11.5%–39%). It may be he presenting arrhythmia and can occur during the electrohysiologic study. Atrial fibrillation during electrophysiologic tudy makes mapping and catheter ablation difficult. Previous eports have described ablation of AV accessory pathways uring atrial fibrillation using an accessory pathway potential r earliest ventricular activation as a guide. Pathway potenial localization can be used to guide ablation of an atriofasicular (Mahaim) pathway during atrial fibrillation. However, ocalization of these potentials is different compared with AV athways, as illustrated in the following case.