Nineteen patients with coronary artery disease were studied to determine the significance of reduced regional myocardial blood flow (50 ml/min per 100 g or less) in areas of abnormal wall motion. Regional myocardial blood flow was measured in four regions of the left ventricle with an Anger camera after the injection xenon-133 into the left main coronary artery. Abnormal wall motion was evaluated with biplane left ventriculography at rest and during postextrasystolic potentiation, a potent inotropic stimulus. Abnormal wall motion was defined as hemiaxis shortening of less than 20 percent. Four hemiaxes were designated as corresponding to the four regions of myocardial blood flow. Of 76 hemiaxes evaluated in the 19 patients, 54 manifested normal wall motion and 22 abnormal wall motion; 8 of the 22 hemiaxes had reduced regional myocardial bood flow. In these 8, hemiaxis shortening increased 6 +/- 2 percent (mean +/- standard error of the mean) above values at rest during postextrasystolic potentiation (with normalization of hemiaxis shortening in only 1 of the 8), compared with an increase of 19 +/- 4 percent (P less than 0.001) in the 12 hemiaxes with borderline regional myocardial blood flow (with normalization of hemiaxis shortening in 9 of the 12, P less than 0.05). These results indicate that the presence of reduced regional myocardial blood flow in areas of abnormal wall motion usually predicts a poor response to post-extrasystolic potentiation, whereas abnormal wall motion without reduced regional myocardial blood flow usually predicts a good response. The combination of reduced regional myocardial blood flow and abnormal wall motion suggests scarred and nonviable myocardium.