1. Cardiovascular Research Center and Cardiology Division; Department of Medicine, Massachusetts General Hospital; Boston Massachusetts USA
2. Cardiovascular Center, Tufts Medical Center; Boston Massachusetts USA
3. Temple Heart and Vascular Institute; Temple University; Philadelphia Pennsylvania USA
4. Harvard Medical School; Boston Massachusetts USA
5. Cardiovascular Medicine Section; Department of Medicine, Boston University; Boston Massachusetts USA
6. Whitaker Cardiovascular Institute; Boston University; Boston Massachusetts USA
7. Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School; Boston Massachusetts USA