1. Department of Medical Biotechnologies, Division of Cardiology, University of Siena, 53100 Siena, Italy
2. Institute of Public Health and Clinical Medicine, Umeå University, 901 87 Umeå, Sweden
3. Department of Cardiovascular Disease-AUSL Romagna, Division of Cardiology, Ospedale S. Maria Delle Croci, 48121 Ravenna, Italy
4. Department of Cardiac Surgery, University of Siena, 53100 Siena, Italy