Electrocardiogram (ECG) is a convenient, economic, and non-invasive detecting tool in myocardial ischemia (MI). And its clinical appearance is mainly exhibited by ST-segment deviation. In the paper, the concepts of Correlation Coefficient Entropy (CCE) and Inverse Correlation Coefficient Entropy (ICCE) were proposed and used to compare the differences in morphology variability between ST segments induced by Heart Rate (HR) and by MI. After the Long-Term ST database (LTST) verification, the obvious results obtained with both methods. Whats more, It showed that CCE was better than ICCE comparatively.