1. Department of Cardiology, West German Heart and Vascular Center Essen, University Duisburg–Essen, Essen, Germany
2. University of Insubria, Varese, Italy
3. Department of Thoracic and Cardiovascular surgery, West German Heart and Vascular Center Essen, University Duisburg–Essen, Essen, Germany
4. “Heart” Department, University Hospital, Salerno, Italy
5. Institute of Medical Informatics, Biometrics and Epidemiology, University Hospital Essen, University Duisburg–Essen, Essen, Germany