[1] Keele Univ, Sch Med, Keele, Staffs, England
[2] Royal Shrewsbury Hosp, Dept Cardiol, Shrewsbury, Salop, England
[3] Univ Hosp North Midlands, Dept Imaging, Stoke On Trent, Staffs, England
[4] Univ Hosp North Midlands, Dept Cardiol, Stoke On Trent, Staffs, England
[5] Univ Hosp North Midlands, Dept Cardiothorac Surg, Stoke On Trent, Staffs, England