1. Department of Cardiothoracic Surgery, Landspitali University Hospital , Reykjavik, Iceland
2. Faculty of Medicine, University of Iceland, Reykjavik , Iceland
3. Department of Cardiothoracic Surgery, Sahlgrenska University Hospital , Gothenburg, Sweden
4. Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, Gothenburg University , Gothenburg, Sweden
5. Department of Cardiology, Skaraborg Hospital Lidköping , Lidköping, Sweden