An ECG system measures and annotates the P-point of an ECG waveform from harmonic waveforms. Electrical impulses are received from a beating heart. The electrical impulses are converted to an ECG waveform. The ECG waveform is converted to a frequency domain waveform, which, in turn, is separated into two or more different frequency domain waveforms, which, in turn, are converted into a plurality of time domain cardiac electrophysiological subwaveforms and discontinuity points between these subwaveforms. The plurality of subwaveforms and discontinuity points are compared to a database of subwaveforms and discontinuity points for normal and abnormal patients. A discontinuity point is identified as the P-point of the ECG waveform from the comparison. Similar measurements are made for the P′-point, I-point, J-point, and T′-point. Distances from these points to the equipotential line are calculated and used to detect blockages leading to myocardial infarction.