Automatic distinguishing between ischemic and heart-rate related transient ST segment episodes in ambulatory ECG records

In ambulatory ECG records, ischemia is manifested by transient ST segment episodes which may or may not be accompanied by increase in heart rate. There are also transient heart-rate related non-ischemic ST segment episodes present which are caused by change in heart rate. The goal of this work was to classify between these two types of ST episodes. The selected features to classify the ST episodes were changes of heart rate, changes of time domain morphologic parameters of the ST segment and changes of the Legendre orthonormal polynomial coefficients of the ST segment, all obtained on 20-second intervals at the beginning and at the extrema of each ST episode. The obtained sensitivity in classifying ischemic versus heart-rate related ST episodes using the LTST DB was 77.9%, while specificity was 73.9%.