[1] Duke Univ, Med Ctr, Duke Clin Res Inst, Dept Med,Div Cardiol, POB 17969, Durham, NC 27715 USA
[2] Univ Calgary, Libin Cardiovasc Inst, Calgary, AB, Canada
[3] Univ Calgary, Obrien Inst Publ Hlth, Calgary, AB, Canada
[4] Duke Univ, Duke Clin Res Inst, Durham, NC USA
[5] Univ N Carolina, Gillings Sch Global Publ Hlth, Chapel Hill, NC USA
[6] Duke Univ, Med Ctr, Div Cardiol, Durham, NC USA
[7] Inova Heart & Vasc Inst, Falls Church, VA USA
[8] Univ Alberta, Canadian VIGOUR Ctr, Edmonton, AB, Canada