Frequency, characteristics, and clinical significance of transient ST segment elevation in patients with acute coronary syndromes.

BACKGROUND Prior investigations of transient myocardial ischaemia have focused on ST depression events. Therefore, the purpose of this analysis was to determine the frequency, characteristics, and clinical significance of transient ST segment elevation in patients with acute coronary syndromes. METHODS A secondary analysis from two prospective studies utilizing 12-lead ST segment monitoring was used to compare ST elevation vs ST depression events. RESULTS Of 868 patients, 177 (20%) had 574 events (242, ST elevation; 332, ST depression). Patients with ST elevation were more likely to have single vessel coronary artery disease, whereas patients with ST depression were more likely to have triple vessel coronary artery disease. ST elevation events were of shorter duration, more often associated with chest pain, and had greater ST changes than ST depression events. There was no difference in clinical outcome between patients with ST elevation vs depression; however, those with ST events were more likely to have adverse hospital outcomes (OR, 3.67) or death (OR, 2.03) than patients without ST events. After controlling for clinical prognostic factors, transient ST events observed with continuous ST monitoring predicted hospital death independently from signs of ischaemia on the initial standard 12-lead ECG. CONCLUSIONS Transient ST elevation is nearly as prevalent as transient ST depression in patients with acute coronary syndromes. Since the vast majority of ST events are brief and otherwise clinically silent, ST segment monitoring is more efficacious in detecting ischaemic events and in predicting adverse clinical outcomes than patients' symptoms or the initial standard 12-lead ECG.