1. From the Divisions of Cardiology (J.P.M., G.R.M.) and Cardiovascular Surgery (D.H., E.M., R.A.J.), Departments of Biomedical Engineering (A.B.) and Biostatistics and Informatics (Y.I.C., R.M.), Children’s National Medical Center, Washington, DC; Divisions of Cardiology (M.A.M.) and Cardiovascular Surgery (G.T., J.L., X.L.), The George Washington University School of Medicine, Washington, DC; and St Jude Medical CRMD, Sylmar, CA (G.A.B.).