1 Center for Interdisciplinary Cardiovascular Sciences, Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital (E.A., M.C.B., S.A.S.), Harvard Medical School, Boston.
2 Center for Excellence in Vascular Biology, Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital (E.A.), Harvard Medical School, Boston.
3 Division of Cardiology, Cardiac Ultrasound Laboratory, Massachusetts General Hospital (R.A.L.), Harvard Medical School, Boston.
4 Imperial College London, United Kingdom (M.H.Y.).