From the Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minn (P.B.B., D.R.H.); the Division of Cardiology, Duke University, Durham, NC (R.H.T., R.M.C.); the Department of Cardiology, Cleveland Clinic, Cleveland, Ohio (E.J.T.); The Department of Cardiovascular Medicine, Flinders Cardiovascular Center, Adelaide, Australia (P.E.A.); and the Department of Cardiology, Beaumont Hospital, Dublin, Ireland (J.H.H.). (At 1999-02-23)