1. Duke Clinical Research Institute, Durham, NC (M.F., S.S., A.F.H., A.D.D.).
2. Division of Cardiology, Duke University Medical Center, Durham, NC (M.F., A.F.H., A.D.D.).
3. Department of Biostatistics and Bioinformatics, Duke University, Durham, NC (H.X., R.A.M.).
4. Section of Cardiology, Veterans Affairs Palo Alto Healthcare System, Palo Alto, CA (P.A.H.).
5. Division of Cardiology, Yale University, New Haven, CT (E.J.V.).
6. Division of Cardiology, Northwestern University, Chicago, IL (C.W.Y.).
7. Division of Cardiology, Ahmanson-UCLA Cardiomyopathy Center, University of California, Los Angeles Medical Center (G.C.F.).