1. Royal Free London NHS Foundation Trust, United Kingdom (D.S.K., T.K., Y.R., L.C., J.T.B., P.S.J., J.G., M.J., L.E.L., R.N., A.W., N.P., M.F.).
2. Institute of Cardiovascular Science, University College London, United Kingdom (D.S.K., J.T.B., J.C.M., N.P.).
3. National Amyloidosis Centre, Division of Medicine, University College London, United Kingdom (L.C., M.F.).
4. Academic Department of Defence Medicine, Royal Centre for Defence Medicine, ICT Centre, Edgbaston, Birmingham, United Kingdom (L.E.L.).
5. Barts Heart Centre, Barts Health NHS Trust, West Smithfield, London, United Kingdom (J.C.M.).
6. National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD (H.X., P.K.).