1. From the Departments of Cardiovascular Medicine (P.S., S.E.N., K.Z., T.C., E.M.T.), Biomedical Engineering (D.G.V.), and Biostatistics and Epidemiology (C.A.-H.), Cleveland Clinic Foundation, Cleveland, Ohio; The Cardiovascular Research Foundation (G.W.S.), New York; NY; William Beaumont Hospital (C.L.G.), Royal Oak, Mich; Virginia Beach General Hospital (J.G.), Virginia Beach, Va; St Francis Medical Center (B.S.C.), Peoria, Ill; and University of Washington (S.R.K.), Seattle; Wash.