[1] Turku Univ Hosp, Heart Ctr, POB 52, FIN-20521 Turku, Finland
[2] Univ Turku, Dept Surg, Turku, Finland
[3] Oulu Univ Hosp, Dept Surg, Oulu, Finland
[4] Univ Oulu, Oulu, Finland
[5] Robert Debre Univ Hosp, Div Cardiothorac & Vasc Surg, Reims, France
[6] Univ Hosp Jean Minjoz, Dept Thorac & Cardio Vasc Surg, Besancon, France
[7] S Camillo Forlanini Hosp, Dept Cardiovasc Sci, Cardiac Surg Unit, Rome, Italy
[8] Hamburg Univ, Heart Ctr, Hamburg, Germany
[9] Verona Univ Hosp, Div Cardiovasc Surg, Verona, Italy
[10] Karolinska Inst, Karolinska Univ Hosp, Dept Mol Med & Surg, Dept Cardiac Surg, Stockholm, Sweden
[11] Paracelsus Med Univ, Cardiovasc Ctr, Nurnberg, Germany
[12] Ctr Clincodiagnost GB Morgagni, Ctr Cuore, Pedara, Italy
[13] St Anna Hosp, Dept Cardiac Surg, Catanzaro, Italy
[14] Univ Genoa, Div Cardiac Surg, Genoa, Italy
[15] Univ Parma, Div Cardiac Surg, Parma, Italy
[16] Ctr Cardiol Fdn Monzino IRCCS, Dept Cardiac Surg, Milan, Italy
[17] Osped Riuniti, Div Cardiac Surg, Trieste, Italy
[18] Ist Super Sanita, Natl Ctr Global Hlth, Rome, Italy
[19] Univ Campania Luigi Vanvitelli, Dept Cardiothorac Sci, Naples, Italy
[20] Univ Leicester, Glenfield Hosp, Dept Cardiovasc Sci, Clin Sci Wing, Leicester, Leics, England