Prognostic value of continuous ST-segment monitoring in patients with non-ST-segment elevation acute coronary syndromes

Abstract

Background: Patients with non-ST-segment elevation acute coronary syndromes constitute a heterogeneous group concerning prognosis. The 12-lead ECG at rest is recommended for early risk stratification but is unable to reflect the dynamic nature of myocardial ischemia and coronary thrombosis. This study investigated whether continuous ST-segment monitoring provides early prognostic information in such patients. Methods: We prospectively studied 183 patients admitted due to chest pain at rest suggestive of an acute coronary syndrome. ST-segment monitoring was performed continuously for 24 hours from admission. Cardiac-specific troponin I levels were determined on admission and every 6 hours for the first 24 hours. The endpoint was defined as death or nonfatal myocardial infarction, whichever occurred first by 30 days follow-up. Results: ST episodes, defined as transient ST deviations of at least 0.1 mV, were detected in 50 patients (27.3%) and associated with worse 30-day outcome: 22.0% endpoint rate compared to 6.8% for patients without ST episodes (P = 0.003). In a multivariate analysis, the presence of ST episodes (hazard ratio, 3.07; 95% CI, 1.26 to 7.46; P = 0.014) and peak troponin I levels > 0.2/μg/L (hazard ratio, 2.65; 95% CI, 1.01 to 6.95; P = 0.048) were independent predictors of prognosis. The combination of ST-segment monitoring and peak troponin I identified patients at low (2.5%, n = 79), intermediate (14.5%, n = 76), and high (25.0%, n = 28) risk for the 30-day endpoint. Conclusions: In patients with non-ST-segment elevation acute coronary syndromes, continuous ST-segment monitoring provides on-line early prognostic information, in addition to troponin I levels.