1. Arrhythmia Section, Cardiology Department, Cardiovascular Institute, Hospital Clínic, University of Barcelona and IDIBAPS (Institut d'Investigació Agustí Pi i Sunyer), C/Villarroel 170, Barcelona, Spain
2. Ospedale Guglielmo da Saliceto, Piacenza, Italy
3. Arrhythmia Unit, Virgen del Rocío University Hospital, Seville, Spain
4. Arrhythmia Unit, Hospital Puerta del Mar, Cádiz, Spain
5. Department of Anatomy and Cell Biology, Faculty of Medicine University of Extremadura, Badajoz, Spain