Value of regional wall motion abnormality in the emergency room diagnosis of acute myocardial infarction: A prospective study using two-dimensional echocardiography

Because regional wall motion abnormality (RWMA) is usually noted during ischemia, we hypothesized that the presence of this finding with two-dimensional echocardiography would be superior to conventional methods of diagnosing acute myocardial infarction (AMI) in the ~ emergency room. We also hypothesized that because the absence of RWMA would probably not be associated with AMI, the use of two-dimensional echocardiography would significantly limit unnecessary hospital admissions. To test these hypotheses, we undertook a prospective study that used two-dimensional echocardiography in 180 patients presenting to the emergency room with symptoms suggestive of AMI. The emergency room physicians were not informed of the two-dimensional echocardiography findings, and their decision to admit or not admit to the hospital was based on conventional clinical and electrocardiographic criteria. Forty patients were not admitted to the hospital and 140 were admitted. Of the 30 patients with enzyme-confirmed AMI, nine had typical ST elevation on the ECG that was consistent with acute injury, three had normal ECGs, and eight had ECGs in the presence of which AMI could not have been diagnosed (left bundle branch block, paced rhythm, or repolarization changes); the rest had nonspecific ECG findings. Of the 29 AMI patients with technically adequate two-dimensional echocardiography studies, two did not demonstrate RWMA and 27 had RWMA, compared with nine with diagnostic ECG changes (p<0.001). Of the 13 patients with in-hospital complications only four had an initial ECG showing ST elevation, and all 13 had RWMA (p<0.001). Of the patients who were not admitted to the hospital, two had AMI and one of them developed a complication. If only patients with RWMA had been admitted, hospital admissions would have been reduced by 32%, and no additional AMI patients and no patient with complications after AMI would have been discharged. We conclude that two-dimensional echocardiography is superior to conventional methods in the emergency room for the diagnosis of AMI, prediction of in-hospital complications, and reduction of unnecessary hospital admissions.