1. From the Division of Biomedical Sciences (T.A.J., P.S.C., A.J.D., M.I.H., I.A.G.) and Division of Clinical Sciences (G.W.C.), St. George's, University of London, London, United Kingdom; NeuroSearch A/S, Ballerup, Denmark (S.P.O., R.S.H.); and The Danish National Research Foundation Center for Cardiac Arrhythmia, The Panum Institute, University of Copenhagen, Copenhagen, Denmark (S.P.O., R.S.H.).