1. Cardiac Arrhythmia and Electrophysiology Unit, Department of Cardiology; Hospital Virgen de la Salud; Toledo Spain
2. Karolinska University Hospital; Karolinska Institutet at Department of Cardiology; Stockholm Sweden
3. Arrhythmia Unit, Department of Cardiology; Complejo Asistencial Universitario de Burgos; Burgos Spain
4. Arrhythmia Unit, Department of Cardiology; Hospital Universitario La Paz; Madrid Spain