[1] Univ Alabama, Div Cardiol, Birmingham, AL USA
[2] NHLBI, Div Heart & Vasc Dis, Bethesda, MD 20892 USA
[3] Rhode Isl Hosp, Div Cardiol, Providence, RI USA
[4] Cedars Sinai Med Ctr, Div Cardiol, Los Angeles, CA 90048 USA
[5] Univ Florida, Div Cardiol, Gainesville, FL USA
[6] W Penn Allegheny Hlth Syst, MCP Hahnemann Sch Med, Div Cardiol, Pittsburgh, PA USA
[7] Univ Pittsburgh, Med Ctr, Cardiovasc Inst, Pittsburgh, PA 15213 USA
[8] Univ Pittsburgh, Dept Epidemiol, Pittsburgh, PA 15213 USA
[9] Univ Pittsburgh, VA Pittsburgh Healthcare Syst, Dept Med, Pittsburgh, PA 15213 USA