1. First Department of Cardiology, Medical School, National and Kapodistrian University of Athens, Hippocration General Hospital, 115 27 Athens, Greece
2. Department of Cardiology and Angiology, Universitatklinikum Essen, 451 47 Essen, Germany
3. Second Department of Adult Cardiac Surgery, Onassis Cardiac Surgery Center, 176 74 Athens, Greece