1. German Society for Thoracic and Cardiovascular Surgery, Langenbeck-Virchow-Haus, Berlin, Germany
2. BQS Institute for Quality and Patient Safety, Hamburg, Germany
3. Clinic for Thoracic and Cardiovascular Surgery, Heart and Diabetes, Center NRW, Bad Oeynhausen, Germany
4. Department for Cardiac, Thoracic and Vascular Surgery, German Heart Center Charité, University Medicine, Germany