1. Department of Medicine, South-Karelia Central Hospital, University of Helsinki , Lappeenranta , Finland
2. Heart and Lung Center, Helsinki University Hospital, University of Helsinki , Helsinki , Finland
3. Cardiovascular Surgery Department, University Hospital Gregorio Marañón , Madrid , Spain
4. Department of Cardiac Surgery, Glenfield Hospital , Leicester , UK
5. Department of Cardiac Surgery, LMU University Hospital, Ludwig Maximilian University , Munich , Germany
6. German Centre for Cardiovascular Research, Partner Site Munich Heart Alliance , Munich , Germany
7. Department of Cardiac Surgery, Hôpitaux Universitaires Henri Mondor, Assistance Publique-Hôpitaux de Paris , Creteil , France
8. Department of Thoracic and Cardiovascular Surgery, University of Franche-Comte , Besancon , France
9. Department of Cardiothoracic Surgery, University Hospital Muenster , Muenster , Germany
10. Department of Cardiovascular Surgery, University Heart and Vascular Center Hamburg , Hamburg , Germany
11. Department of Cardiac Surgery, Third Faculty of Medicine, Charles University and University Hospital Kralovske Vinohrady , Prague , Czech Republic
12. Division of Cardiac Surgery, Cardio-thoracic and Vascular Department, Azienda Sanitaria Universitaria Giuliano Isontina , Trieste , Italy
13. Cardiothoracic Department, University Hospital , Udine , Italy
14. Cardiac Surgery, Molinette Hospital, University of Turin , Turin , Italy
15. Department of Cardiovascular Surgery, Hospital Clínic de Barcelona, University of Barcelona , Barcelona , Spain
16. Department of Cardiac Surgery, Centre Hospitalier Annecy Genevois , Epagny Metz-Tessy , France
17. Department of Cardiac Surgery, Centre Cardiologique du Nord de Saint-Denis , Paris , France
18. Liverpool Centre for Cardiovascular Sciences, Liverpool Heart and Chest Hospital , Liverpool , UK
19. Department of Cardiac Surgery, Ziekenhuis Oost Limburg , Genk , Belgium
20. Department of Cardiac Surgery, Martin Luther University Halle-Wittenberg , Halle , Germany
21. Division of Cardiac Surgery, University of Verona Medical School , Verona , Italy
22. Research Unit of Surgery, Anesthesia and Critical Care, University of Oulu , Oulu , Finland