Q waves on the electrocardiogram, according to Schinkel et al.(A-15), are often considered to be reflective of irreversiblyscarred myocardium. These researchers assert, however, that thereare some indications that residual viable tissue may be present inQ-wave-infarcted regions. Their study of 150 patients with chronicelectrocardiographic Q-wave infarction found 202 dysfunctionalQ-wave regions. With dobutamine stress echocardiography (DSE), theynoted that 118 of these 202 regions were viable with informationfrom the DSE testing. Construct a 90 percent confidence intervalfor the proportion of viable regions that one might expect to finda population of dysfunctional Q-wave regions.