1. Section of Cardiovascular Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, USA.
2. The Dartmouth Institute for Clinical Practice and Health Policy, Lebanon, New Hampshire, USA.
3. Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA.
4. Palo Alto Medical Foundation Research Institute, Palo Alto, California, USA.
5. Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA.