1 Adult Congenital Heart Centre and National Centre for Pulmonary Hypertension, Royal Brompton Hospital, London, United Kingdom; Autonomous University of Barcelona, Barcelona, Spain. Electronic address: a.pires@rbht.nhs.uk.
2 Adult Congenital Heart Centre and National Centre for Pulmonary Hypertension, Royal Brompton Hospital, London, United Kingdom; National Heart & Lung Institute, Imperial College London, United Kingdom.