T wave alternans detection: a simulation study and analysis of the European ST-T database

The detection of T wave alternans (TWA) in surface ECG signals has been recognized as a marker of electrical instability, and is hypothesized to be related with patients at increased risk for ventricular arrhythmias. In this paper we present a evaluation study of a method for detecting ST-T complex alternans based on the Complex Demodulation approach (CD), and its application to the European ST-T Database. To study the performance of this detector a simulated ECG signal was obtained adding controlled alternans to a database of young, healthy subjects ECGs. In this way, the ECG signal contained noise and non-alternans ST-T variability coming from real recordings. The detector applied to the European ST-T Database (where ischemic ST and T episodes were manually annotated by physicians), detected 148 TWA episodes, from which 82 (55.4%) overlapped with ischemic episodes, while in 12.0% of the annotated ischemic episodes, a TWA was detected. A significant correlation between ST elevation and the existence and magnitude of TWA was found