1. Duke Clinical Research Institute, Durham, North Carolina2Department of Medicine, Division of Cardiology, Duke University, Durham, North Carolina
2. VA Eastern Colorado Health Care System, Denver4Department of Medicine, Division of Cardiology, University of Colorado School of Medicine, Aurora
3. Department of Medicine, Division of Cardiology, Virginia Commonwealth University, Richmond
4. San Francisco Veterans Affairs Medical Center, San Francisco, California7Department of Medicine, Division of Cardiology, University of California, San Francisco, San Francisco