1. From the Cardiovascular Division, Brigham and Women’s Hospital, Harvard Medical School, Boston, Mass (K.C.K., C.L.F., Y.S.C., M.I.P., E.R.E., P.H.S.); Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Mass (Y.S.C., M.J., A.B.B., E.R.E.); Mechanical and Industrial Engineering, Northeastern University, Boston, Mass (A.U.C.); and Department of Health Services, University of Washington, Seattle (C.M.).