1. Division of Cardiology Department of Medicine Duke University Medical Center Durham North Carolina
2. Duke Clinical Research Institute Durham North Carolina
3. Department of Clinical Medicine Aalborg University Aalborg Denmark
4. Department of Health Science and Technology Aalborg University Aalborg Denmark
5. Unit of Epidemiology and Biostatistics Aalborg University Hospital Aalborg Denmark
6. Department of Clinical Physiology Karolinska Institute, and Karolinska University Hospital Stockholm Sweden