From the Department of Cardiac Medicine (P.P., T.P.C., M.P., D.O., K.W.-P., D.H., S.D.A., A.J.S.C.), Imperial College School of Medicine, National Heart and Lung Institute, London, UK, and Centro Medico di Gussago (M.V., A.G.) and Centro Medico di Veruno (R.C., G.M.), Fondazione “Salvatore Maugeri,” Italy. (At 1997-10-21)