1. From the Joseph B. Whitehead Department of Surgery, Division of Cardiothoracic Surgery, Carlyle Fraser Heart Center, Emory University School of Medicine, Atlanta, Ga (W.A.C., V.H.T., R.A.G., R.P.); University of Pennsylvania Medical Center, Philadelphia (C.R.B.); and Outcomes Research and Assessment Group, Duke Clinical Research Institute, Duke University, Durham, NC (S.M.O., L.A.S., E.D.P.).