1. Clinic of Cardiology, National Heart Hospital, 65 Konioviza Str., 1309 Sofia, Bulgaria
2. Central hospitalier Châlons-en-Champagne, 51 Rue du Commandant Derrien, 51000 Châlons-en-Champagne, France
3. Laboratory Department, National Heart Hospital, 65 Konioviza Str., 1309 Sofia, Bulgaria