[1] Univ Leicester, Leicester Royal Infirm, Dept Cardiovasc Sci, Leicester LE2 7LX, Leics, England
[2] Umea Univ Hosp, Dept Publ Hlth & Clin Med, S-90185 Umea, Sweden
[3] Univ London Imperial Coll Sci Technol & Med, Int Ctr Circulatory Hlth, London, England