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 myocardial ischaemia by continuous ST analysis, the maximum ST vector magnitude 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 patients admitted to our CCU with suspected unstable angina pectoris, were included in the study. During the first 24 h the patients were monitored for ischaemic episodes with computerized vectorcardiography, using a MIDA 1000 system. Twenty seven (14%) of the 195 patients died or had a non-fatal myocardial infarction within 1 year and the maximum ST vector magnitude among those patients was, on average, 201 μV compared with 118 μV in patients who survived 1 year free of myocardial infarction (P < 0.01). The area under the ST vector magnitude trend curve was, on average, 1598 μV min compared with 164 μV min (P < 0.01). By multivariate analysis, the maximum ST vector magnitude emerged as a superior predictor of death or myocardial infarction compared with the area under the ST vector magnitude trend curve and the number of ST vector magnitude and ST change vector magnitude episodes. The maximum ST vector magnitude and age were independent predictors of death or non-fatal myocardial infarction within 1 year. Conclusion: Maximum ST vector magnitude during the first 24 h of vectorcardiographic monitoring seems to be a strong predictor of subsequent death or non-fatal myocardial infarction.