1. Department of Cardiovascular Surgery, University Heart and Vascular Center Hamburg, University Hospital Eppendorf , Martinistr. 52, 20246 Hamburg , Germany
2. Department of Cardiac Surgery, Kerckhoff-Klinik , Bad Nauheim , Germany
3. Department of Cardiology and Critical Care Medicine, Asklepios Klinik St Georg , Hamburg , Germany
4. Department of Cardiology, Heart Center Brandenburg and Brandenburg Medical School , Bernau , Germany
5. Department of Cardiac Surgery, University Heart Center Dresden , Dresden , Germany
6. Department of Cardiovascular Surgery, MediClin Heart Center , Coswig , Germany
7. Division of Electrophysiological Surgery, Johanniter-Hospital Duisburg-Rheinhausen , Duisburg , Germany
8. Department of Cardiac Surgery, Heidelberg University Hospital , Heidelberg , Germany
9. Department of Cardiac Surgery, University Hospital Bonn , Bonn , Germany
10. Department of Cardiac Surgery, Schüchtermann-Klinik , Bad Rothenfelde , Germany
11. Department for Cardiothoracic Surgery, Heart and Vessel Center Bad Bevensen , Bad Bevensen , Germany
12. Department for Cardiovascular Surgery, Hospital of the Philipps-University of Marburg , Marburg , Germany
13. Department of Cardiac Surgery, Heart Center Bad Segeberg , Bad Segeberg , Germany
14. Department of Cardiovascular Surgery, Helios Clinic for Heart Surgery , Karlsruhe , Germany
15. Department of Cardiothoracic Surgery, University Hospital Jena , Jena , Germany
16. Division of Cardiothoracic Surgery, University Hospital of Magdeburg , Magdeburg , Germany
17. Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School , Hannover , Germany
18. Department of Cardiology, St Marien Hospital , Siegen , Germany
19. Department of Cardiac Surgery, University Hospital Essen , Essen , Germany
20. Department of Cardiac Surgery, Robert-Bosch Hospital , Stuttgart , Germany
21. Department of Cardiothoracic and Vascular Surgery, University Hospital Mainz , Mainz , Germany
22. Department for Cardiac Insufficiency and Device Therapy, Albertinen-Hospital , Hamburg , Germany
23. Department of Thoracic and Cardiovascular Surgery, Georg August University Medical Center , Göttingen , Germany
24. Department of Cardiac Surgery, MediClin Heart Institute , Lahr/Baden , Germany