1. From the Department of Cardiovascular Medicine, Cleveland Clinic Foundation, Cleveland, Ohio (J.S., D.B., E.J.T.); University of North Carolina, Chapel Hill, North Carolina (S.R.S.); Mayo Clinic, Rochester, Minn (P.B.B.); University of Cincinnati, Cincinnati, Ohio (D.J.K.); and Johns Hopkins University, Baltimore, Md (V.L.S.).