Conventional analysis of electrocardiograms (ECGs) is based on its shape and the height and interval of its principal inflection points. The weighting of the waveforms and estimation of the action potential at the source of the ECG (the inverse problem) have been longstanding issues affecting the diagnosis of heart disease by ECG. The approach of Tsukada’s group is a tensor-based cardiography that uses a simple equation, the difference between two pairs of cumulative distribution functions (CDFs), to analyze the time series variance of collective myocardial APs from the ECG. By fitting this equation to the R and T waves, they obtain a set of metrics that represent beat-to-beat dynamic variance of polarization and repolarization of the epi and endocardium. Their study on ECGs from myocardial ischemia during coronary intervention shows that there are abnormalities in the tensor elements associated with repolarization, which appear earlier and more prominently than conventional changes.