1. Department of Cardiovascular Medicine, Mayo College of Medicine, Mayo Clinic, 200 First Street, SW, Rochester, MN 55905, USA
2. VA New England Healthcare System, Boston University School of Medicine, VA Boston Campus, 150 S. Huntington Avenue, Boston, MA 02130, USA
3. Department of Cardiovascular Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
4. Division of Cardiovascular Medicine, Brigham & Women’s Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA
5. Department of Cardiovascular Medicine, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy
6. Department of Cardiovascular and Pulmonary Sciences, Catholic University of the Sacred Heart, Rome, Italy
7. Royal Brompton & Harefield Hospitals, Heart Division and Imperial College, National Heart & Lung Institute, London, UK