1. Department of Internal Medicine, General Hospital of Athens “Elpis”, Athens, Greece;
2. Third Department of Internal Medicine, Athens School of Medicine, National and Kapodistrian University of Athens, Sotiria General Hospital, Athens, Greece;
3. Second Department of Cardiology, Laboratory of Cardiac Electrophysiology, “Evangelismos” General Hospital of Athens, Athens, Greece;
4. Department of Hygiene and Epidemiology, Aristotle University of Thessaloniki, School of Medicine, Thessaloniki, Greece;
5. First Department of Cardiology, University of Ioannina, School of Medicine, Ioannina, Greece