1. Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
2. Department of Epidemiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
3. Department of Cardiology and Cardiothoracic Surgery, Catharina Hospital Eindhoven, Eindhoven, The Netherlands
4. Harteraad, Den Haag, The Netherlands
5. Division of Heart & Lungs, Department of Cardiology, Utrecht University Medical Center, Utrecht University, P.O. Box 85500, 3508 GA Utrecht, The Netherlands