[1] Golden Jubilee Natl Hosp, Glasgow, Lanark, Scotland
[2] Aarhus Univ Hosp, Dept Cardiol, DK-8000 Aarhus, Denmark
[3] Southampton Univ Hosp, Southampton, Hants, England
[4] Paul Stradins Clin Hosp, Latvian Ctr Cardiol, Riga, Latvia
[5] Liverpool Heart & Chest Hosp, Liverpool, Merseyside, England
[6] Brighton Univ Hosp, Sussex Cardiac Ctr, Brighton, E Sussex, England
[7] Sussex Univ Hosp, Sussex Cardiac Ctr, Brighton, E Sussex, England
[8] Univ Oulu, Dept Internal Med, Div Cardiol, Oulu, Finland
[9] Flinders Univ S Australia, Dept Cardiol, Adelaide, SA 5001, Australia
[10] Univ Hosp Tromsoe, Dept Cardiol, Tromso, Norway
[11] Gentofte Univ Hosp, Dept Cardiol, Gentofte, Denmark