1. Division of Cardiology, University of Texas Southwestern Medical Center, Dallas (D.J.K.).
2. UCLA Division of Cardiology, Ahmanson-UCLA Cardiomyopathy Center, Los Angeles, CA (G.C.F.).
3. Division of Cardiology, Stanford School of Medicine, Palo Alto, CA (P.A.H.).
4. Duke Clinical Research Institute, Duke University Medical Center, Durham, NC (P.J.S., D.L., A.H.).
5. Department of Cardiology, Northwestern Fienberg School of Medicine, Chicago, IL (C.Y.).
6. Brigham and Women’s Hospital Heart & Vascular Center and Harvard Medical School, Boston, MA (D.L.B.).