1. Arrhythmology Unit, Ospedale San Giovanni Calibita, Fatebefratelli Isola Tiberina, Via Ponte Quattro Capi 39, Rome 00186, Italy
2. Clinic for Electrophysiology, Herz—und Diabeteszentrum Nordrhein-Westfalen, Georgstr. 11, 32545 Bad Oeynhausen, Ruhr University Bochum, Germany