1. Department of Cardiovascular Surgery, University Heart Center Freiburg, Bad Krozingen, Germany
2. Faculty of Medicine, Albert Ludwigs University Freiburg, Freiburg, Germany
3. Institute of Medical Biometry and Informatics, University of Heidelberg, Heidelberg, Germany
4. Department of Cardiac Surgery, Schuechtermann Clinic, Bad Rothenfelde, Germany
5. Department of Cardiothoracic and Vascular Surgery, University Hospital, Johannes Gutenberg University, Mainz, Germany
6. Clinic of Cardiothoracic Surgery, Klinikum Augsburg, Augsburg, Germany
7. Department of Cardiac Surgery, University Hospital, LMU Munich, Munich, Germany
8. Department of Cardiac Surgery, Heidelberg University Hospital, Heidelberg, Germany
9. Department for Thoracic and Cardiovascular Surgery, University Hospital Tübingen, Eberhard Karls University, Tübingen, Germany
10. Department of Cardiovascular Surgery, University Heart Center Hamburg, Hamburg, Germany
11. Department of Thoracic and Cardiovascular Surgery, Johann Wolfgang Goethe University, Frankfurt/Main, Germany
12. Department of Cardiac Surgery, Leipzig Heart Center, Leipzig, Germany
13. Department of Adult and Pediatric Cardiovascular Surgery, Giessen University Hospital, Giessen, Germany