1. Department of Thoracic, Cardiac and Vascular Surgery, University Hospital Tübingen, Tübingen, Germany
2. Institute of Medical Biostatistics, Epidemiology and Informatics (IMBEI), Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
3. Department of Cardiac Surgery, Leipzig Heart Center, Leipzig, Germany
4. Department of Cardiothoracic and Vascular Surgery, Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany