SERIAL ELECTROCARDIOGRAMS FOR CHEST PAIN PATIENTS WITH INITIAL NONDIAGNOSTIC ELECTROCARDIOGRAMS - IMPLICATIONS FOR THROMBOLYTIC THERAPY

Objectives: To determine the proportion of acute myocardial infarction (AMI) patients without ST-segment elevation who subsequently develop ST-segment elevation during their hospital courses; and to compare dem ographics and presenting features of AMI patient subgroups: those with initial ST-segment elevation, those with in-hospital ST-segment eleva tion, and those with no ST-segment elevation. Methods: A retrospective cohort analysis of admitted chest pain patients who had a hospital di scharge diagnosis of AMI was performed. Each chart was examined for in itial ECG interpretation, serial ECG analysis, patient age, gender, ca rdiac risk factors, in-hospital survival, time between sequential ECGs , and number of ECGs performed within the-first 48 hours of hospital a dmission. Results: Of the 114 charts reviewed, 20 patients had ECGs me eting thrombolytic criteria on arrival. Of the 94 AMI patients who had nondiagnostic ECGs on arrival, 19 (20%) subsequently developed ECG ch anges meeting thrombolytic criteria. Seven patients developed these ch anges within eight hours of the initial EGG, four from eight to 12 hou rs after, two from 12 to 24 hours after, and six more than 24 hours af ter. Most patients who had documented AMIs did not develop ECG criteri a for thrombolytic therapy during their hospitalizations. Male gender and smoking history were more commonly associated with late ST-segment elevation for those presenting with nondiagnostic ECGs. All the patie nts who had late diagnostic ECG changes survived to hospital discharge . Serial ECGs were performed more frequently in the group who had init ially diagnostic ECGs and least frequently in the group who did not de velop ST-segment elevation during their hospitalizations. Conclusions: Most patients with AMI do not meet ECG criteria for the administratio n of thrombolytic therapy. A significant minority (20%) of the admitte d chest pain patients with subsequently confirmed AMIs developed ECG c riteria for thrombolytics during their hospitalizations. Further atten tion to such patients who have delayed ST-segment elevation is warrant ed. A standardized in-hospital serial ECG protocol should be considere d to identify admitted patients who develop criteria for thrombolytic or other coronary revascularization therapy.