1. Cardiovascular Division, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA (M.V., B.L.C., S.D.S.).
2. Institute of Cardiology, Department of Medical and Surgical Specialties, Radiological Sciences, and Public Health, University of Brescia, Italy (R.M.I.).
3. Ahmanson-UCLA Cardiomyopathy Center, University of California, Los Angeles (G.C.F.).
4. British Heart Foundation Cardiovascular Research Centre, University of Glasgow, UK (J.J.V.M.).