Thirty-three patients with chest pain despite angiographically normal coronary arteries underwent both coronary flow studies during pacing and resting and exercise gated blood pool scintigraphy. During atrial pacing after administration of ergonovine, those patients developing their typical chest pain demonstrated significantly lower great cardiac vein flow (97 ± 31 vs 150 + 33 ml/ min, p < .001), higher coronary resistance (1.27 -+-0.43 vs 0.77 ± 0.18 mm Hg/ml/min, p < .005), and less lactate consumption (30.5 ± 22.0 vs 69.7 + 41.1 mM * ml/min, p < .005) and a higher left ventricular end-diastolic pressure after pacing (20 + 4 vs 12 ± 1, p < .001) compared with those without pain and in the absence of significant luminal narrowing of the epicardial coronary arteries. The 26 patients with abnormal vasodilator reserve demonstrated reduced left ventricular ejection fraction during exercise (58 ± 8%) compared with the seveni patients with appropriate vasodilator reserve (66 ± 4%, p < .05) and with a group of 52 control patients of similar age and sex distribution and free of known heart disease (66 ± 10%, p < .001). In addition, 12 of the 26 patients with abnormal vasodilator reserve demonstrated exercise-induced regional wall motion abnormalities. Many of these patients also manifested impaired left ventricular diastolic filling at rest compared with the control subjects (peak filling rate 2.6 + 0.7 vs 3.2 -+ 0.7 end-diastolic volume/sec, p < .005). Thus, patients with chest pain resulting from abnormal vasodilator reserve demonstrate abnormalities of left ventricular systolic and diastolic function suggestive of myocardial ischemia. Circulation 71, No. 2, 218-226, 1985. MUCH DEBATE has focused on whether or not patients with chest pain despite normal epicardial coronary arteries truly experience myocardial ischemia. I6 Several investigators have found that many of these patients clearly have a noncardiac cause of their pain, including esophageal,7 8 chest wall,9 and psychosomatic causes.'0 However, others have found many such patients to have abnormal exercise electrocardiograms, 11-18,