1. From the Cardiac Centers of Louisiana (J.K.G.), Shreveport, La; Case Western Reserve University (I.L.P.), Cleveland, Ohio; University of Maryland (S.S.G.), Baltimore, Md; University of California, San Francisco School of Medicine (P.C.D.), San Francisco, Calif; and Wallenberg Laboratory for Cardiovascular Research (J.C.W.), Sahlgrenska University Hospital, Göteborg, Sweden, and AstraZeneca (J.C.W.), Mölndal, Sweden.