1. Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin School of Medicine and Public Health, Madison
2. Duke Clinical Research Institute, Duke University Medical Center, Durham, North Carolina
3. Gill Heart and Vascular Institute, University of Kentucky, Lexington
4. Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor
5. Ann Arbor Veterans Affairs Health System, Ann Arbor, Michigan
6. Department of Cardiovascular Medicine, Heart, Vascular and Thoracic Institute, Cleveland Clinic, Cleveland, Ohio