[1] Freeman Rd Hosp, Cardiothorac Dept, Newcastle Upon Tyne NE7 7DN, Tyne & Wear, England
[2] Univ Hertfordshire, Sch Life & Med Sci, Hatfield AL10 9AB, Herts, England
[3] Minneapolis Heart Inst Fdn, Minneapolis, MN 55407 USA
[4] Humanitas Clin & Res Ctr IRCCS, Dept Invas Cardiol, I-20089 Milan, Italy
[5] St Georges Univ Hosp NHS Fdn Trust, Dept Cardiol, London SW17 0QT, England
[6] Newcastle Univ, Translat & Clin Res Inst, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England