1. Department of Cardiology, University of Groningen, University Medical Center Groningen, PO Box 30.001, 9700 RB Groningen, the Netherlands
2. Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
3. Duke University Medical Center, Durham, NC, USA
4. University of Maastricht, Maastricht Medical Center, Maastricht, the Netherlands
5. Aarhus University Hospital, Aarhus, Denmark
6. Montefiore Weiler Hospital, New York, NY, USA
7. Universitätsklinikum Würzburg, Würzburg, Germany
8. Liverpool Heart and Chest Hospital, Liverpool, UK
9. Hospital Clinic, Universitat de Barcelona, Barcelona, Spain