1 Cardiology Department, Essex Cardiothoracic Centre, Basildon and Thurrock University Hospitals NHS Trust, Basildon, UK; Anglia Ruskin School of Medicine, Chelmsford, UK. Electronic address: rupertsimpson@nhs.net.
2 Cardiology Department, Essex Cardiothoracic Centre, Basildon and Thurrock University Hospitals NHS Trust, Basildon, UK; Anglia Ruskin School of Medicine, Chelmsford, UK.
3 Cardiology Department, Essex Cardiothoracic Centre, Basildon and Thurrock University Hospitals NHS Trust, Basildon, UK; Anglia Ruskin School of Medicine, Chelmsford, UK. Electronic address: thomas.keeble2@nhs.net.
4 Cardiology Department, Essex Cardiothoracic Centre, Basildon and Thurrock University Hospitals NHS Trust, Basildon, UK.
5 Cardiology Department, Essex Cardiothoracic Centre, Basildon and Thurrock University Hospitals NHS Trust, Basildon, UK; Division of Anaesthetics, University of Cambridge, UK.