Does the emergency room electrocardiogram identify patients with suspected myocardial infarction who are at low risk of acute complications?

Abstract

To determine the early morbidity of patients admitted to the coronary care unit (CCU) with inconclusive evidence of acute myocardial infarction, the prognostic value of the emergency room electrocardiogram (ECG) was examined prospectively in a blinded fashion in 410 patients presenting with acute chest pain. One hundred and forty one patients (34.4%) had an ECG that was normal, showed ST segment changes less than 1 mm, or was unchanged from a previous recording (group 1). The remaining patients (65.6%, group 2) had ECGs considered abnormal. Thirty-nine patients in group 1 and 226 in group 2 had confirmed infarction. There was one CCU death in group 1 (0.7%) versus 27 (10.0%) in group 2 (p less than 0.001) and the overall hospital mortality for group 1 was 2.1% versus 13.0% in group 2 (p less than 0.001). Twenty-eight patients (19.9%) from group 1 suffered complications in the CCU versus 155 (57.6%) from group 2 (p less than 0.001). No life-threatening arrhythmias occurred in group 1 versus occurrence in 47 patients (17.5%) in group 2 (p less than 0.001). The need for acute intervention was also less for group 1 versus group 2 patients, 14 (9.9%) and 85 (31.6%) respectively (p less than 0.001) with no patient requiring electrical cardioversion in group 1. It is concluded that the emergency room ECG can reliably identify a group of low risk patients presenting with suspected myocardial infarction and so help in establishing priority for admission to the CCU. Furthermore, the risk-benefit of thrombolytic therapy in these low risk patients appears unacceptable.