Is This a Normal ECG?
By Ken Grauer, MD
Professor Emeritus in Family Medicine, College of Medicine, University of Florida
Dr. Grauer is the sole proprietor of KG-EKG Press, and publisher of an ECG pocket brain book.
Figure — ECG from a patient with atypical chest pain.
Scenario: The ECG in the Figure was obtained from a patient with atypical chest pain. Is this a normal ECG? If not, why not?
Interpretation: The rhythm is sinus bradycardia and arrhythmia. The PR, QRS, and QT intervals are all normal. The axis is +30 degrees. There is no chamber enlargement.
Regarding Q-R-S-T Changes — A small and narrow q wave is seen in lead aVL. Transition is slightly delayed, with the R wave only becoming taller than the S wave between lead V4-to-V5. The most remarkable finding on this ECG is ST segment flattening with slight ST depression in multiple leads.
It should be emphasized that the amount of actual ST segment depression on this tracing is minimal. It is no more than 1 mm in the inferior leads. That said, there is no denying that some ST segment depression is present. Even in leads in which there is no ST depression at all (i.e., in leads V2 through V6), ST-T waves are not normal. Instead, there is subtle-but-real ST segment straightening in the precordial chest leads, whereas there should normally be a smooth, gradual transition between the end of the ST segment and the beginning of the T wave.
Bottom Line: This ECG is not normal. Instead, there is diffuse nonspecific ST segment flattening and slight ST depression. These changes are subtle but real. Clinical correlation is essential for knowing how to interpret this ECG finding. This patient may have coronary disease — possibly even severe coronary disease with ischemia. On the other hand, these changes are not acute and they could be due in part or in combination to any of the other potential causes of ST depression (drug effect, electrolyte disorder, hyperventilation, acutely ill patient, etc.). We simply cannot tell on the basis of this single ECG.