Prognostic value of maximum ST-vector magnitude during the first 24 h of vectorcardiographic monitoring in patients with unstable angina pectoris

Aims To assess the prognostic importance of alternate ways of quantifying m yocardial ischaemia by continuous ST analysis, the maximum ST vector magnit ude and the area under the ST vector magnitude trend curve during the first 24 h of continuous ST monitoring. Methods and Results During a 22-month period from 1991 to 1993, 195 patient s admitted to our CCU with suspected unstable angina pectoris, were include d in the study. During the first 24 h the patients were monitored for ischa emic episodes with computerized vectorcardiography, using a MIDA 1000 syste m. Twenty seven (14%) of the 195 patients died or had a non-fatal myocardia l infarction within 1 year and the maximum ST vector magnitude among those patients was, on average, 201 mu V compared with 118 mu V in patients who s urvived 1 year free of myocardial infarction (P < 0.01). The area under the ST vector magnitude trend curve was, on average, 1598 mu Vmin compared wit h 164 mu Vmin (P<0.01). By multivariate analysis, the maximum ST vector mag nitude emerged as a superior predictor of death or myocardial infarction, c ompared with the area under the ST vector magnitude trend curve and the num ber of ST vector magnitude and ST change vector magnitude episodes. The max imum ST vector magnitude and age were independent predictors of death or no n-fatal myocardial infarction within 1 year. Conclusion Maximum ST vector magnitude during the first 24 h of vectorcardi ographic monitoring seems to be a strong predictor of subsequent death or n on-fatal myocardial infarction.