1. Cardiac, Thoracic and Vascular Department; Fondazione IRCCS Policlinico San Matteo; Piazza Golgi 1 27100 Pavia Italy
2. Division of Cardiology; Fondazione Salvatore Maugeri, IRCCS; Veruno Italy
3. Service of Biometry & Statistics; Fondazione IRCCS, Policlinico San Matteo; Pavia Italy
4. Cardiac, Thoracic and Vascular Department; University of Pisa; Pisa Italy
5. Department of Biomedical and Surgical Sciences, Cardiology Section; University of Verona; Verona Italy
6. Division of Cardiology; Fondazione Salvatore Maugeri, IRCCS; Torino Italy