1. William Harvey Research Institute, NIHR Barts Biomedical Research Centre, Queen Mary University of London, Charterhouse Square, United Kingdom (K.F., J.A.C., S.E.P.).
2. Barts Heart Centre, St Bartholomew’s Hospital, Barts Health NHS Trust, London, United Kingdom (K.F., S.E.P.).
3. Advanced Heart Failure and Transplant Unit, Royal Papworth Hospital NHS Foundation Trust, Cambridge, United Kingdom (C.C., P.C., S.B., S.P.).
4. NIHR Oxford Biomedical Research Centre, Division of Cardiovascular Medicine, University of Oxford, United Kingdom (S.K.P., S.N.).