1. From the Arrhythmia Unit and Electrophysiology Laboratory, Ospedale S Raffaele, Milano, Italy (P.D.B., G.M., P.V., F.B.); Arrhythmia Section, Thorax Institute, Hospital Clínic, University of Barcelona, Barcelona, Spain (J.B., A.B.); Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands (K.Z., A.P.W.); Hospital Universitario La Paz, Madrid, Spain (J.M.); Cardiology Department, Na Homolce Hospital, Prague, Czech Republic (P.N.); and Unité de Rythmologie et de Stimulation...