Clinical significance of high frequency QRS potentials in myocardial infarction: analysis based on power spectrum of lead III.

Power spectrum analysis of ECG lead III QRS potentials using the Fast Fourier Transform technique was performed in 10 normal subjects and nine patients with inferior wall myocardial infarction (IWMI). A relative lowering in both low and high frequency QRS potentials was observed in the infarct group, in agreement with previous studies on power spectrum of lead II. However, contrary to earlier conclusions, the lowering was independent of a general attenuation in QRS voltages. Discriminant analysis of the frequency components showed that the high frequency components (190-310 Hz) were able to discriminate better between the two groups than the low frequency components (10-120 Hz).