1. From Cardiovascular Engineering, Inc, Norwood, MA (V.B., J.D.G., A.A.T., G.F.M.); Icelandic Heart Association, Kopavogur, Iceland (S.S., T.A., V.G.); Leiden University Medical Center, The Netherlands (J.J.M.W., A.d.R.); University of Iceland, Reykjavik (T.A., V.G.); and National Institute on Aging, National Institutes of Health, Bethesda, MD (L.J.L., T.B.H.).