1. Massachusetts General Hospital, Boston
2. Duke Clinical Research Institute, Durham, North Carolina
3. Emory University, Atlanta, Georgia
4. Duke Heart Center, Duke University School of Medicine, Durham, North Carolina
5. Cleveland Clinic, Cleveland, Ohio
6. Washington University School of Medicine, St Louis, Missouri
7. Mayo Clinic, Rochester, Minnesota
8. Brigham and Women’s Hospital, Boston, Massachusetts
9. University of Vermont Medical Center, Burlington
10. Thomas Jefferson University, Philadelphia, Pennsylvania
11. National Heart, Lung, and Blood Institute, Bethesda, Maryland
12. Stony Brook Medical Center, Stony Brook, New York