1. Cardiac Surgery Unit, Cardiocentro Ticino Institute, EOC, 6900 Lugano, Switzerland
2. Department of Cardiology, Cardiocentro Ticino Institute, EOC, 6900 Lugano, Switzerland
3. Service of Clinical Epidemiology & Biometry, IRCCS Fondazione Policlinico San Matteo, 27100 Pavia, Italy
4. Biomedical Faculty, University of Italian Switzerland (USI), 6900 Lugano, Switzerland
5. School of Medicine, University of Zurich, 8006 Zurich, Switzerland