1. From the Department of Internal Medicine (K.A.B., B.D.P., U.V., S.L.K., R.S.W.), and the Divisions of Cardiovascular Diseases (K.A.B., B.D.P., U.V., S.L.K., R.S.W.), Biostatistics (A.G.R.), and Cardiothoracic Surgery (C.M.), Mayo Clinic College of Medicine, Rochester, Minn.