Magnetocardiographic demonstration of complex ventricular preexcitation resulting in ablation failure

The Wolff-Parkinson-White (WPW) syndrome affects 1 to 3 persons per 1000. Catheter ablation (CA) is nowadays proposed as the preferred therapy (with success in more than 90% of cases) and ECG is the most used non-invasive method for classification and to choose the interventional approach. However, in some cases, difficulties might arise during the electrophysiologic study (EP), due to unexpected complex (or multiple) ventricular preexcitation (VP), especially paraseptal. Therefore several non-invasive methods have been proposed to improve preoperative localization and to minimize the risk of failure and prolonged exposure to radiation. Magnetocardiographic mapping (MCG) is an alternative, not yet familiar to clinicians,although its diagnostic value been recently underlined. Compared with other noninvasive methods, MCG provides better accuracy and unrivalled three-dimensional (3D) electroanatomical integration and imaging (EAI) to localize ventricular preexcitation. Here we report two WPW patients, come to our observation after unsuccessful ablation attempted in other institutions. In both, re-interventional ECG classification of VP was uncertain. Post-interventional MCG provided 3D imaging of complex VP, which, if available before catheterization, could have probably avoided the ablation failures.