Phase-Rectified Signal Averaging for automatic detection of QRS fragmentation

QRS fragmentation is visible in the ECG signal as the presence of one or more deflections, notches or slurs in the QRS complex. The presence of QRS fragmentation is strongly related with the myocardial fibrosis or scarrings and has been associated with adverse outcome in patients. Since detection of fragmented QRS complexes is mainly done on a visual basis, its practical use is limited. We propose an automatic method to detect the QRS fragmentation based on Phase-Rectified Signal Averaging (PRSA). The method calculates the PRSA curve, approximates it with a linear fit and derives four parameters related to the slope and linear fit. Analysis of a dataset from the University Hospitals of Leuven with 268 patients shows that all four parameters are significantly different in fragmented channels compared to normal channels (p<0.001). Furthermore, Cohen's d suggests that three out of four parameters have at least a large effect size (d > 0.8).