1. Department of Cardiology; University Medical Center Groningen, University of Groningen; PO Box 30.001 9700RB Groningen The Netherlands
2. University of Pavia, Fondazione Salvatore Maugeri; Pavia Italy
3. Medtronic Europe; Tolchenaz Switzerland
4. Stavanger University Hospital, University of Bergen; Norway
5. University of Gothenborg; Göteborg Sweden