1. National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
2. Department of Medicine, University of Iceland, Reykyavik, Iceland
3. Akureyri Hospital, Akureyri, Iceland
4. Heart and Vascular Institute of UPMC, University of Pittsburgh, Pittsburgh, Pennsylvania
5. The Heart Center, St Francis Hospital, State University of New York at Stony Brook, Stony Brook
6. Alaska Heart Institute, Anchorage
7. Icelandic Heart Association, Kópavogur, Iceland
8. National Institute on Aging, National Institutes of Health, Bethesda, Maryland