1. Division of Cardiac Surgery, Cardiothoracic Department, University Hospital of Udine, Udine, Italy
2. Health Management Department, University Hospital of Udine, Udine, Italy
3. Department of Hygiene and Clinical Epidemiology, University Hospital of Udine, Udine, Italy
4. Division of Cardiac Surgery, Department of Emergencies and organ transplantation, University of Bari, Bari, Italy
5. Division of Cardiac Surgery, Department of Surgery, Dentistry, Paediatrics and Gynaecology, University of Verona Medical School, Verona, Italy