1. Cardiac Unit, Great Ormond Street Hospital NHS Foundation Trust, London, UK
2. Population Policy and Practice Programme, University College London Institute of Child Health, London, UK
3. Clinical Operational Research Unit, University College London, London, UK
4. Cardiac Surgery Department, Birmingham Children’s Hospital NHS Foundation Trust, Birmingham, UK
5. National Institute for Cardiovascular Outcomes Research, University College London, London, UK
6. Faculty of Medicine and Health, University of Leeds, Leeds, UK
7. Paediatric Cardiac Unit, Royal Brompton and Harefield Hospitals NHS Trust, London, UK
8. Department of Paediatrics, Northampton General Hospital NHS Trust, Northampton, UK
9. Primary Care Department, Queen Mary University of London, London, UK