1 Barts Heart Centre, West Smithfield, London, United Kingdom. Electronic address: c.monkhouse@nhs.net.
2 Glenfield Hospital, Leicester, United Kingdom.
3 Barts Heart Centre, West Smithfield, London, United Kingdom.
4 Barts Heart Centre, West Smithfield, London, United Kingdom; Institute of Cardiovascular Science, University College London (UCL), London, United Kingdom.