[1] Univ Colorado Anschutz Med Campus, Aurora, CO 80045 USA
[2] Duke Clin Res Inst, Durham, NC USA
[3] Duke Univ, Sch Med, Div Cardiol, Durham, NC USA
[4] Weill Cornell Med, Div Cardiol, New York, NY USA
[5] Yale Sch Med, New Haven, CT USA
[6] Northwestern Univ, Chicago, IL 60611 USA
[7] Ronald Reagan Univ Calif Los Angeles, Med Ctr, Los Angeles, CA USA
[8] Rocky Mt Reg VA Med Ctr, Aurora, CO 80045 USA
[9] Duke Univ, Dept Biostat & Bioinformat, Durham, NC USA