[1] Hosp Univ Penn, Div Cardiovasc, 3400 Spruce St, Philadelphia, PA 19104 USA
[2] Univ Penn, Leonard Davis Inst Hlth Econ, Philadelphia, PA 19104 USA
[3] Univ Penn, Penn Cardiovasc Outcomes Qual & Evaluat Res Ctr, Cardiovasc Inst, Philadelphia, PA 19104 USA
[4] Univ Penn, Perelman Sch Med, Div Gen Internal Med, Philadelphia, PA 19104 USA
[5] Univ Penn, Div Cardiovasc Surg, Philadelphia, PA 19104 USA
[6] Baylor Coll Med, Houston, TX 77030 USA
[7] Univ Colorado, Sch Med, Div Cardiol, Aurora, CO USA
[8] Beth Israel Deaconess Med Ctr, Richard & Susan Smith Ctr Outcomes Res Cardiol, Boston, MA 02215 USA
[9] Corporal Michael J Crescenz VA Med Ctr, Philadelphia, PA USA