Automatic detection of ST-T complex changes on the ECG using filtered RMS difference series: Application to ambulatory ischemia monitoring

A new detector is presented which finds changes in the repolarization phase (ST-T complex) of the cardiac cycle, It operates by applying a detection a lgorithm to the filtered root mean square (rms) series of differences betwe en the beat segment (ST segment or ST-T complex) and an average pattern seg ment. The detector has been validated using the European ST-T database, whi ch contains ST-T complex episodes manually annotated by cardiologists, resu lting in sensitivity/positive predictivity of 85/86%, and 85/76%, for ST se gment deviations and ST-T complex changes, respectively, The proposed detec tor has a performance similar to those which have a more complicated struct ure. The detector has the advantage of finding both ST segment deviations a nd entire ST-T complex changes thereby providing a wider characterization o f the potential ischemic events. A post-processing stage, based on a cross- correlation analysis for the episodes in the rms series, is presented. With this stage subclinical events with repetitive pattern were found in around 20% of the recordings and improved the performance to 90/85%, and 89/76%, for ST segment and ST-T complex changes, respectively.