1. Cardiology Department, General Hospital G. Papanikolaou, 57010 Thessaloniki, Greece
2. Cardiology Department, AHEPA University General Hospital, 54636 Thessaloniki, Greece
3. Department of Biochemical Sciences, Pomeranian Medical University, 70-204 Szczecin, Poland
4. Great Ormond Street Hospital, London WC1N 3JH, UK