1. From the Center for Cardiovascular Health Services Research (D.H.D., M.K., R.R., J.D.G., W.M.L., J.R.B., H.P.S.), Tufts Medical Center, Boston, Mass; Emergency Medicine (A.S.), Cambridge Health Alliance, Cambridge, Mass; and Emergency Medicine (M.C.R., W.A.P.), UMassMemorial Medical Center, Worcester, Mass.