Electrocardiographic Ischemic Patterns Without Coronary Artery Disease

¹ The Institute for Medical Research, Cedars of Lebanon Hospital, Los Angeles; Department of Medicine, University of California School of Medicine, Los Angeles and City of Hope Medical Center, Duarte, California.

ST segment deviations (elevation and depression) can be indicative of myocardial ischemia or injury secondary to coronary artery disease. In a wide variety of clinical conditions, however, these ST changes are "non-ischemic," reversible by appropriate therapy and should not be interpreted as pathognomonic of coronary artery disease. Clinical conditions showing these ST changes without myocardial ischemia are reviewed in this paper.

It is postulated that ST segment deviation, whether or not the result of myocardial ischemia is related to changes in potassium and sodium gradients across the myocardial cell membrane. It is further postulated that an increased transmembrane gradient of either of these ions produces ST segment depression and that a decreased transmembrane gradient produces ST segment. elevation. Clinical and experimental evidence is presented supporting these postulates. However, there is little doubt that factors other than sodium and potassium are involved.