[1] Oulu Univ Hosp, POB 21, Oulu 90029, Finland
[2] Pontchaillou Univ Hosp, Div Cardiothorac & Vasc Surg, Rennes, France
[3] Univ Hosp Jean Minjoz, Dept Thorac & Cardiovasc Surg, Besancon, France
[4] Karolinska Univ Hosp, Karolinska Inst, Dept Mol Med & Surg, Dept Cardiothorac Surg & Anesthesiol, Stockholm, Sweden
[5] Verona Univ Hosp, Div Cardiovasc Surg, Verona, Italy
[6] Paracelsus Med Univ, Dept Cardiac Surg, Klinikum Nurnberg, Nurnberg, Germany
[7] St Anna Hosp, Dept Cardiac Surg, Catanzaro, Italy
[8] Hosp S Camillo Forlanini, Dept Cardiosci, Unit Cardiac Surg, Row, Italy
[9] Univ Leicester, Glenfield Hosp, Dept Cardiovasc Sci, Clin Sci Wing, Leicester, Leics, England
[10] Ctr Cuore Morgagni, Pedara, Italy
[11] Univ Naples 2, Dept Cardiothorac Sci, Div Cardiac Surg, Naples, Italy
[12] Osped Riuniti, Div Cardiac Surg, Trieste, Italy