1. From the Centre for Heart Rhythm Disorders (CHRD), University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia (A.N.G., R.M., S.N., A.G.B., H.S.A., P.S.); Discipline of Medicine, Flinders University and Flinders Medical Centre, Bedford Park, Australia (J.B.S., S.G., A.C.); SA Pathology, Adelaide, Australia (J.F.); and Imricor Medical Systems, Burnsville, MN (D.S., T.L.).