1. Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Faculty of Medicine and Health Sciences , Box 8905, NO-7491 Trondheim , Norway
2. Clinic of Cardiology, St. Olavs hospital, Trondheim University Hospital , Trondheim , Norway
3. Clinic of Medicine, Levanger Hospital, Nord-Trøndelag Hospital Trust , Levanger , Norway
4. School of Human Movement and Nutrition Science, University of Queensland , Saint Lucia , Queensland , Australia