[1] Univ Michigan, Sch Med, Frankel Cardiovasc Ctr, Ann Arbor, MI 48109 USA
[2] Univ Michigan, Sch Med, Dept Internal Med, Inst Healthcare Policy & Innovat, Ann Arbor, MI USA
[3] Harvard Med Sch, Massachusetts Gen Hosp, Ctr Vasc Emergencies, Dept Emergency Med, Boston, MA USA
[4] Northwestern Univ, Feinberg Sch Med, Dept Emergency Med, Chicago, IL 60611 USA
[5] St Louis Univ, Sch Med, Div Pulm Crit Care & Sleep Med, St Louis, MO 63103 USA
[6] Univ Penn Med, Lancaster Gen Hlth, Div Cardiol, Lancaster, PA USA
[7] Harvard Med Sch, Massachusetts Gen Hosp, Div Hematol & Oncol, Dept Med, Boston, MA USA
[8] Harvard Med Sch, Massachusetts Gen Hosp, Div Cardiol, Sect Vasc Med,Dept Med, Boston, MA USA
[9] Univ Penn, Perelman Sch Med, Penn Cardiovasc Outcomes Qual & Evaluat Res Ctr, Philadelphia, PA 19104 USA