1. From the Division of Cardiovascular Diseases (W.K.S., J.M.T., K.M.B., A.J., P.A.B., T.M.M., B.J.G., S.C.H., R.L.F.), the Department of Emergency Medicine (W.W.D., P.A.S., D.G.G., A.E.W.), and the Division of Biostatistics (D.O.H.), Mayo Clinic, Rochester, Minn.