1. Department of Medicine, Duke University Medical Center, Durham, NC, USA
2. Duke Clinical Research Institute, Durham, NC, USA
3. Department of Medicine, University of Texas Southwestern, Dallas, TX, USA
4. Department of Medicine, Durham VA Medical Center, Durham, NC, USA
5. Department of Medicine, Libin Cardiovascular Institute, University of Calgary, Alberta, CA, USA
6. Robert and Suzanne Tomsich Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland, OH, USA