1. Duke Clinical Research Institute, Duke University Medical Center, Durham, NC (M.Z., G.M.G., P.Z., D.M.W., S.V.R., T.Y.W.).
2. Division of Cardiology, Department of Medicine, NYU Langone Medical Center‚ New York (N.R.S.).
3. Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO (A.P.A.).