1. Department of Cardiac Surgery, S. Croce Hospital, Cuneo, Italy
2. National Centre for Global Health, Italian Health Institute, Rome, Italy
3. Heart and Lung Center, Helsinki University Hospital, Helsinki, Finland
4. Research Unit of Surgery, Anesthesiology and Critical Care, University of Oulu, Oulu, Finland
5. Department of Surgery, University of Turku, Turku, Finland
6. Agenzia Regionale per i Servizi Sanitari Regionali, Rome, Italy
7. Department of Epidemiology, Città della Salute e della Scienza, University of Turin, Turin, Italy
8. Unit of Cardiac Surgery, IRCCS Policlinico S. Donato, University of Milan, S. Donato Milanese, Italy