[1] Univ Hosp Cologne, Dept Cardiothorac Surg, Kerpener Str 62, D-50937 Cologne, Germany
[2] Justus Liebig Univ Giessen, Dept Cardiac Surg, Kerckhoff Clin, Campus Kerckhoff,Benekestr 2-8, D-61231 Bad Nauheim, Germany
[3] Univ Hosp Cologne, Inst Med Stat & Computat Biol, Cologne, Germany
[4] Ruhr Univ Hosp Bergmannsheil, Dept Cardiothorac Surg, Bochum, Germany
[5] Dept Cardiac Surg, Bad Neustadt an der Saale, Germany
[6] Univ Hosp Essen, West German Heart & Vasc Ctr Essen, Dept Thorac & Cardiovasc Surg, Essen, Germany
[7] Ruhr Univ Bochum, Clin Thorac & Cardiovasc Surg, Heart & Diabet Ctr North RhineWestphalia, Bad Oeynhausen, Germany
[8] Univ Hosp Aachen, Dept Thorac & Cardiovasc Surg, Aachen, Germany
[9] Univ Hosp Munster, Dept Cardiac & Thorac Surg, Munster, Germany
[10] Univ Heart Ctr Hamburg, Dept Cardiovasc Surg, Hamburg, Germany
[11] Otto Von Guericke Univ, Dept Cardiothorac Surg, Magdeburg, Germany
[12] Univ Hosp Cologne, Dept Cardiol, Cologne, Germany