1 Royal Free Hospital, London, United Kingdom; University of Trieste, Trieste, Italy; European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart-ERN GUARD-Heart, Trieste, Italy.
2 Royal Free Hospital, London, United Kingdom.
3 Brigham and Women's Hospital, Boston, Massachusetts, USA.
4 Royal Free Hospital, London, United Kingdom. Electronic address: m.fontana@ucl.ac.uk.