Frequency domain analysis (FDA) and time domain analysis (TDA) are techniques for the diagnostic interpretation of signal averaged ECG. To overcome the limitations of TDA, such as noise and conduction disturbances, FDA has been developed. But the reproducibility of FDA, especially spectral temporal mapping analysis, results are significantly lower than that of TDA. We examine the difference of two methods, and the role in high risk patients with myocardial infarction. Low amplitude signal (LAS) and area ratio (AR) are independent predictors of inducible sustained monomorphic ventricular tachycardia (SMVT) by programmed ventricular stimulation. The combined use of TDA and FDA enhanced the accuracy in predicting inducible SMVT.