[1] Univ Coll London Hosp, Heart Hosp, London, England
[2] Yale Univ, Sch Med, Div Cardiol, New Haven, CT USA
[3] Univ British Columbia, St Pauls Hosp, Dept Cardiol, Vancouver, BC V5Z 1M9, Canada
[4] Univ Hosp Geneva HUGE, Dept Cardiol, Geneva, Switzerland
[5] Kantonsspital Luzern, Dept Cardiol, Luzern, Switzerland
[6] London Sch Hyg & Trop Med, Dept Med Stat, London WC1, England
[7] Brighton & Sussex Univ Hosp, Div Anesthesiol, Brighton, E Sussex, England
[8] Kings Coll Hosp London, Dept Cardiothorac Surg, London, England
[9] Brighton & Sussex Univ Hosp, Div Cardiol, Brighton, E Sussex, England