1. Department of Internal Medicine III, Division of Cardiology, Pneumology, Angiology and Intensive Care, University of Cologne, Cologne, Germany.
2. Department of Anesthesiology and Intensive Care Medicine, University Hospital of Cologne, Cologne, Germany.
3. Department of Cardiothoracic Surgery, Heart Center of the University of Cologne, Cologne, Germany.
4. Institute of Medical Statistics Epidemiology, University of Cologne, Cologne, Germany.
5. Department of Internal Medicine and Cardiology, Ev. Klinikum Köln-Weyertal, Cologne, Germany.