1. Duke Clinical Research Institute, Durham, NC (G.M.G., M.T.R., A.F.H., W.S.J.).
2. Duke University Medical Center, Durham, NC (M.T.R., A.F.H., W.S.J.).
3. Division of Cardiovascular Medicine; Cardiovascular Research Institute; Department of Medicine, Stanford University, California (R.A.H.).
4. Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN (D.M.).