1. Department of Cardiology, University of Groningen, University Medical Center Groningen, P.O. Box 30.001, 9700 RB Groningen, The Netherlands
2. Department of Cardiology, Maastricht University Medical Center, Maastricht, The Netherlands
3. Department of Cardiology, Radboud University Medical Center, Nijmegen, The Netherlands
4. Department of Cardiology and Electrophysiology, Leipzig Heart Institute, Leipzig, Germany