1. From the Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia (S.N., L.W., A.N.G., P.K., D.C., A.G.B., R.M., M.B., G.D.Y., P.S., K.C.R.-T.); and Data Management and Analysis Centre, The University of Adelaide, Adelaide, Australia (T.S.).