1. the Faculty of Medicine, Institute of Nursing Science, University of Freiburg, Freiburg, Germany
2. German Heart Center Berlin, Freiburg, Germany
3. Heart and Diabetes Center North-Rhine Westphalia, University Hospital of the Ruhr University Bochum, Bad Oeynhausen, Germany
4. Medical Center—University of Freiburg, University Heart Center Freiburg—Bad Krozingen, Germany
5. Leipzig Heart Center, Freiburg, Germany
6. Faculty of Medicine and Medical Center, Institute of Medical Biometry and Statistics, University of Freiburg, Freiburg, Germany.