1. Department of Cardiology, Na Homolce Hospital, Prague, Czech Republic;
2. Department of Cardiology, Karolinska University Hospital, Stockholm, Sweden;
3. Department of Medicine, Karolinska Institutet, Stockholm, Sweden;
4. Department of Medical Engineering, School of Technology and Health, KTH, Royal Institute of Technology, Stockholm, Sweden;
5. Department of Clinical Physiology, Sunderby Hospital, Luleå, Sweden