1Pacing & Electrophysiology Unit, Cardiology Department, Coimbra's Hospital and University Center, Coimbra, Portugal
2Cardiology Department, Hospital da Luz Arrábida, V. N. Gaia, Portugal
3Cardiology Department, University Hospital Center of São João, Porto, Portugal
4Cardiology Department, Vila Nova de Gaia e Espinho Hospital, V. N. Gaia, Portugal
5Cardiology Department, Clinique Saint Pierre, Perpignan, France
6Cardiac Arrhythmia Service, The Harvard Thorndike PE Institute, Beth Israel Deaconess Medical Center, Harvard Medical Scholl, Boston, USA
7ICBR, Faculty of Medicine, University of Coimbra, Coimbra, Portugal