1. Academic Medical Center Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, The Netherlands (F.V.Y.T., R.E.K., A.A.M.W.)
2. Cardiology Department, Na Homolce Hospital, Prague, Czech Republic (P.N., J.P., L.S.)
3. Kerckhoff Heart and Thorax Center, Bad Nauheim, Germany (J.S.)
4. Helmsley Electrophysiology Center, Mount Sinai School of Medicine, New York, NY (V.Y.R.)