1. Clinical Ergospirometry, Exercise & Rehabilitation Laboratory, 1st Critical Care Medicine Department, Evangelismos Hospital, National and Kapodistrian University of Athens, 10676 Athens, Greece
2. Department of Cardiology, “Helena Venizelou” Hospital, 10676 Athens, Greece
3. 1st Department of Respiratory Medicine, Sotiria Chest Hospital, School of Medicine, National and Kapodistrian University of Athens, 11527 Athens, Greece
4. Cardiac Surgery Intensive Care Unit, Onassis Cardiac Surgery Center, 17674 Athens, Greece
5. Department of Cardiology, 417 Army Share Fund Hospital of Athens (NIMTS), 11521 Athens, Greece