Electroanatomical mapping and radiofrequency ablation of an accessory pathway associated with a large aneurysm of the coronary sinus.

We report a case of a patient with a left posteroseptal accessory pathway associated with a coronary sinus (CS) aneurysm. The patient had undergone two previous failed ablation attempts at other institutions despite multiple radiofrequency applications delivered within and outside the CS aneurysm. Electroanatomical mapping was performed and allowed delineation of the three-dimensional anatomy of the aneurysm, so as to identify the ventricular insertion site, and to permit successful ablation of the pathway without any complications.