1. Department of Cardio-thoracic Surgery, Leiden University Medical Center, Leiden, Netherlands
2. Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
3. Board of the Netherlands Heart Registry, Utrecht, Netherlands
4. Department of Statistics, Leiden University Medical Center, Leiden, Netherlands
5. Department of Cardio-thoracic Surgery, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands