995-18 Coronary Endothelial Dysfunction in Patients with Normal Coronary Angiography and Abnormal Functional Tests

Coronary endothelial dysfunction is characterized by a vasoconstrictive response to the endothelial-dependent vasodilator acetylcholine. In patients with normal coronary angiograms, stress-induced myocardial ischemia has been considered to be false-positive on functional testing. Since coronary vasodilatation during exercise is endothelial-dependent, this study was designed to test the hypothesis that patients with stress-induced myocardial ischemia and normal coronary angiograms may demonstrate coronary endothelial-dependent vasoconstriction to acetylcholine. Thus, coronary angiography with graded doses of intracoronary acetylcholine was performed in 30 patients who had undergone previous stress functional tests (14 exercise thallium, eight exercise echocardiography, four dipyridamole thallium, and four dobutamine echocardiography). Twenty patients had an abnormal functional test (Group 1), and 10 patients had normal functional tests serve as a control group (Group 2).AcetylcholineMyocardial Ischemia by Functional TestingPositive (Group 1)Negative (Group 2)Vasoconstriction190Vasodilation110TOTAL2010p<0.001This study demonstrates that patients with stress-induced myocardial ischemia and normal coronary angiograms represent coronary endothelial dysfunction