[1] Univ Massachusetts, Sch Med, Dept Med, Div Cardiovasc Med, Worcester, MA 01655 USA
[2] Concord Hosp, Sydney, NSW, Australia
[3] Univ Michigan, Ann Arbor, MI 48109 USA
[4] Duke Univ, Med Ctr, Durham, NC USA
[5] Royal Infirm, Edinburgh, Midlothian, Scotland