1. Cardiovascular Division, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA
2. Framingham Heart Study, Framingham, MA
3. Department of Exercise and Health Sciences, University of Massachusetts, Boston, MA
4. National Heart, Lung and Blood Institute, Framingham, MA
5. Division of Radiology, Beth Israel Deaconess Medical Center, Boston, MA
6. Cardiology Section, Department of Medicine, Boston Veteran's Administration Healthcare System, Boston, MA