[1] Papworth Hosp NHS Fdn Trust, Dept Cardiol, Papworth Everard, Cambs, England
[2] Univ Hosp Birmingham NHS Fdn Trust, Queen Elizabeth Hosp, Birmingham, W Midlands, England
[3] Univ Birmingham, Birmingham, W Midlands, England
[4] Univ London Imperial Coll Sci Technol & Med, Hammersmith Hosp, Cardiothorac Dept, London, England
[5] Brighton Univ Hosp, Brighton, E Sussex, England