1. Centre of Clinical Heart Research, Oslo University Hospital, Oslo, Norway;
2. Epidemiology and Biological Statistics, Independent Health Research Unit, Oslo, Norway;
3. Oslo Centre of Biostatistics and Epidemiology, Oslo University Hospital, Oslo, Norway;
4. Department of Cardiovascular Surgery, Oslo University Hospital, Oslo, Norway;
5. Department of Cardiovascular Surgery, LHL Hospital, Gardemoen, Norway