[1] Castle Hill Hosp, Hull York Med Sch, Dept Cardiol, Kingston Upon Hull, N Humberside, England
[2] Imperial Coll, Royal Brompton & Harefield Hosp, Natl Heart & Lung Inst, London, England
[3] Univ Glasgow, Robertson Ctr Biostat & Clin Trials, Glasgow, Lanark, Scotland
[4] Anglia Ruskin Univ, Fac Med Sci, Cambridge, England