1. From the Departments of Cardiology (K.N., V.v.D., H.v.W., R.v.E., B.d.P., P.A.D., F.W.) and Medical Physiology (B.d.P.), University Medical Center Utrecht, Utrecht, The Netherlands; Department of Rhythmology, Alfried Krupp Krankenhaus, Essen, Germany (K.N.); St Jude Medical, Veenendaal, The Netherlands (H.v.W.); and ICIN-Netherlands Heart Institute, Utrecht, The Netherlands (P.A.D.)