1. From the Cardiovascular Imaging and Clinical Research Core Laboratory (L.d.l.F., L.R.P., V.G.D.-R.), the Center for Cardiovascular Research (D.P.K.), the Cardiovascular Division, Department of Medicine (L.d.l.F., L.R.P., D.P.K., R.J.G., V.G.D.-R.), and the Cardiovascular Imaging Laboratory, Mallinckrodt Institute of Radiology (P.H., R.J.G.), Washington University School of Medicine, St Louis, Mo.