[1] Univ Massachusetts, Sch Med, Dept Med, Div Cardiovasc Med, Worcester, MA 01655 USA
[2] Univ Massachusetts, Sch Med, Ctr Outcomes Res, Worcester, MA 01655 USA
[3] Concord Hosp, Sydney, NSW, Australia
[4] Hop Bichat, Serv Cardiol, F-75877 Paris, France
[5] Univ Toronto, St Michaels Hosp, Div Cardiol, Canadian Heart Res Ctr, Toronto, ON M5B 1W8, Canada
[6] Univ Toronto, St Michaels Hosp, Div Cardiol, Terrence Donnelly Heart Ctr, Toronto, ON M5B 1W8, Canada
[7] Royal Edinburgh Infirm, Edinburgh, Midlothian, Scotland