INVESTIGATION OF THE MECHANISM OF CHEST PAIN IN PATIENTS WITH ANGIOGRAPHICALLY NORMAL CORONARY-ARTERIES USING TRANSESOPHAGEAL DOBUTAMINE STRESS ECHOCARDIOGRAPHY

Objectives. The present study sought to determine whether myocardial c ontractile abnormalities accompany the development of chest pain in pa tients with normal coronary angiograms. Background. The mechanism of c hest pain in patients with angina despite a normal coronary arteriogra m is controversial. Although previous studies postulated the existence of coronary microvascular dysfunction, others failed to find evidence of myocardial ischemia, and recent studies have demonstrated abnormal cardiac sensitivity in these patients that can lead to chest pain on a nonischemic basis. Methods. Seventy patients (26 men and 44 women, m ean age 49 +/- 10 years) with angina-like chest pain and angiographica lly normal coronary arteries underwent exercise treadmill testing, rad ionuclide angiography at rest and during exercise, thallium stress tes ting and transesophageal dobutamine stress echocardiography, The resul ts of exercise treadmill testing and stress echocardiography were comp ared with those obtained in 26 normal control subjects (19 men and 7 w omen, mean age 56 +/- 7 years). Results. Abnormalities consistent with myocardial ischemia were noted in 31% of the patients during exercise treadmill testing, in 16% during exercise radionuclide angiography an d in 18% during thallium stress testing. The findings of the radionucl ide studies were not concordant with one another and were not related to the presence of repolarization changes during exercise testing. Dur ing infusion of dobutamine, chest pain developed in 59 patients (84%) and in none of the control subjects (p < 0.0001); repolarization chang es occurred in 22 patients (34%) and in 2 control subjects (8%) (p < 0 .04). None of the patients or the control subjects developed regional mall motion abnormalities with dobutamine. The quantitative myocardial contractile response to dobutamine was similar in patients and contro l subjects, with an 80% power to detect a 25% difference in systolic m all thickening at the maximal dose of dobutamine. Conclusions. There w as no agreement in the results of noninvasive tests in our patients. D espite the frequent provocation of chest pain and electrocardiographic abnormalities with dobutamine, the patients demonstrated a quantitati vely normal myocardial contractile response without development of wal l motion abnormalities, These observations strongly suggest that myoca rdial ischemia is not the cause of chest pain in patients with a norma l coronary arteriogram. (C) 1997 by the American College of Cardiology .