[1] Harvard Univ, Brigham & Womens Hosp, Sch Med, Div Cardiovasc, Boston, MA 02115 USA
[2] Univ Oslo, Internal Med Res Inst, Oslo, Norway
[3] Rijnland Hosp, Leiderdorp, Netherlands
[4] Bergen Univ Hosp, Dept Clin Chem, Div Endocrinol, Bergen, Norway
[5] Univ Toronto, Toronto Gen Hosp, Div Cardiol, Toronto, ON M5G 1L7, Canada