Contrast Stress Echocardiography for the Diagnosis of Coronary Artery Disease in Patients With Chest Pain but Without Acute Coronary Syndrome: Incremental Value of Myocardial Perfusion

Abstract

The inappropriate admission of patients with noncardiac chest pain is an enormous cost to society. Myocardial perfusion imaging (MPI) could prove effective in the risk stratification of patients in whom acute coronary syndromes are ruled out by electrocardiography and troponin levels, thanks to its incremental sensitivity beyond that of wall motion (WM) criteria for obstructive coronary artery disease, and still maintain the excellent safety profile of dipyridamole-atropine stress echocardiography (DASE). The aim of this study was to test this hypothesis using WM and MPI (WM + MPI) in consecutive patients admitted to a chest pain unit. Patients presenting to a chest pain unit between January and June 2008 with chest pain and in whom acute coronary syndromes had been ruled out by normal electrocardiography and cardiac enzyme levels underwent DASE with the addition of contrast MPI. Four hundred consecutive patients were enrolled. WM + MPI resulted in 71 true-positive findings, compared with 46 by stand-alone WM (P < .05).True-positive results accounted for 46 of 50 positive test results for WM and 71 of 82 positive test results for WM + MPI (positive predictive value, 92% vs 87%; P = NS). In the subset of patients who underwent angiography (n = 116), the sensitivity, specificity, and accuracy for WM compared with WM + MPI were 63% versus 97% (P < .05), 91% versus 74% (P < .05), and 73% versus 89% (P < .05). The addition of MPI to standard DASE increased true-positive test results by >50% compared with WM criteria, with a nonsignificant difference in positive predictive value. Twenty-five patients were diagnosed with obstructive coronary artery disease thanks only to isolated MPI abnormalities; the cardiac origin of their chest pain would have been mistakenly "ruled out" on the basis of the absence of WM abnormalities.