1. From the Division of Cardiovascular Medicine (Q.R.P., M.M., B.A.H., J.K.E., M.A.V., J.R.S., S.J.K.), Department of Internal Medicine (M.M., J.S.B.), and Department of Biostatistics (M.G.M.), Henry Ford Hospital, Detroit MI; and the Division of Cardiovascular Disease and Internal Medicine, Mayo Clinic, Rochester MN (Q.R.P.).