1. From the Department of Clinical & Experimental Cardiology, Heart Center, Amsterdam Medical Center, University of Amsterdam, Noord-Holland, The Netherlands (T.F.B., A.-F.B.E.Q., A.A.W., R.E.K.); and Helmsley Cardiac Arrhythmia Service, Icahn School of Medicine at Mount Sinai, New York, NY (M.A.M., C.P., S.R.D., V.R., J.M.W.).