Department of Cardiology, Oslo University Hospital, Rikshospitalet, Norway; University of Oslo, Oslo, Norway; K.G. Jebsen Cardiac Research Center and Center for Heart Failure Research, Faculty of Medicine, University of Oslo, Oslo, Norway. Electronic address: krvbra@ous-hf.no. Department of Cardiology, Oslo University Hospital, Rikshospitalet, Norway. Department of Cardiology, Oslo University Hospital, Rikshospitalet, Norway; University of Oslo, Oslo, Norway; K.G. Jebsen Cardiac Research Center and Center for Heart Failure Research, Faculty of Medicine, University of Oslo, Oslo, Norway. Department of Cardiology, Oslo University Hospital, Rikshospitalet, Norway; K.G. Jebsen Cardiac Research Center and Center for Heart Failure Research, Faculty of Medicine, University of Oslo, Oslo, Norway.