1. Division of Cardiovascular Diseases, Faculty of Medicine, University Clinical Center of the Republic of Srpska, University of Banja Luka, Banja Luka, Bosnia and Herzegovina;
2. Cardio Internal Medicine Outpatient Clinic, Banja Luka, Bosnia and Herzegovina;
3. Clinical Center of Serbia, Belgrade, Serbia;
4. Faculty of Medicine, University of Belgrade, Belgrade, Serbia;
5. CNR Institute of Clinical Physiology of Pisa, Pisa, Italy