1. From the Heart Rhythm Centre, National Institute for Health Research (NIHR) Cardiovascular Research Unit, Heart Rhythm Centre, Royal Brompton and Harefield Hospitals, National Heart and Lung Institute, Imperial College London, London, United Kingdom (S.P., J.W.E.J., S.H., C.B., H.K., L.M., E.N., J.P.F., V.M., T.W.); CV Path Institute, Gaithersburg, MD (R.V., R.K.); and Department of Cardiology, National Heart Centre Singapore, Singapore (E.L.).