ST Depression

ECG Features

Figure 1: ECG Strip[1]

ST depression and ST elevation are forms of ST segment abnormalities caused by myocardial ischaemia or infarction. The ST segment is the section of the ECG between the end of the S-wave and the beginning of the T-wave. ST depression occurs when the ST segment is depressed in comparison to the PR segment. Specifically, the ST segment represents "the interval between ventricular depolarization and repolarization.''[2]

Clinical Significance[3]

  • Clinical circumstances surrounding ECG changes are crucial in diagnosing the specificity of ST segment abnormalities.
  • Various factors, in addition to myocardial disease, can affect ST segment configuration:
    • Drugs
    • Electrolyte abnormalities of potassium, magnesium, and calcium
    • Neurogenic factors, such as hypoglycemia and hyperventilation
    • Atrial repolarization
    • Ventricular conduction abnormalities and rhythms beginning in the ventricles

ECM Features

See ST Segment Abnormalities for Figure 2 format explanation

Figure 2: ECM Analysis, Record e0106, Lead V3[4][5] The ST segment is a darker shade of blue than the PR segment on the ECM, indicating more negative amplitude and the presence of ST depression.

ECM Examples

Additional Information


  1. Klabunde, R. E. (2016). Electrocardiogram ST segment changes [Online image]. Retrieved July 20, 2016, from
  2. The ST Segment. (n.d.). Retrieved July 27, 2016, from
  3. ST Segment Abnormalities. (n.d.). Retrieved August 05, 2016, from
  4. European ST-T Database. (1992). Retrieved July, 2016, from
  5. Goldberger AL, Amaral LAN, Glass L, Hausdorff JM, Ivanov PCh, Mark RG, Mietus JE, Moody GB, Peng C-K, Stanley HE. PhysioBank, PhysioToolkit, and PhysioNet: Components of a New Research Resource for Complex Physiologic Signals. Circulation101(23):e215-e220 [Circulation Electronic Pages;]; 2000 (June 13).