Evaluating rest ECG amplitude changes using the ECG variability contour method

The "ECG variability contour" (EVC) method was studied with real life rest ECG. Three 1-min long, 12-lead, rest ECG formed the data sets. Mean ECG complex was calculated for each data set, and subtracted from it and the other 2 data sets, forming 9 residue matrices. Residue matrix variables were: (1) EVC reflecting ECG variability (2) normalized cumulative sum (NCS) reflecting consistent amplitude changes, and (3) the number of points of the NCS lying outside EVC, which defined a significant ECG change. 1052 ECG leads (92 examinees) were analyzed. In 73% of leads the temporal distance between the data set and the subtracted mean ECG had an effect. <1 point (0.5%) of the NCS was located outside the EVC. Using the EVC method, it was demonstrated that consistent ECG amplitude changes may be accurately localized to the corresponding ECG component, and these changes were rare at rest.