The 12-lead ECG in the figure below belongs to a 50-year-old man who presented to the ED with new-onset chest discomfort. His initial ECG (that was taken when he arrived in the ED) was the tracing shown in the ECG Review that appeared in the January 15 issue of Internal Medicine Alert. No more than minimal ST-T wave changes were seen on the initial ECG. The tracing in the figure below was obtained just 8 minutes later.
The ECG in the figure illustrates how rapidly ST-T wave changes may develop during active stages of acute ST elevation myocardial infarction. In this case, no more than 8 minutes was necessary for the ECG to evolve from a minimally abnormal tracing to the dramatic picture of diffuse ST-T wave changes seen here.
The rhythm is sinus. Obvious ST segment elevation occurs in leads I, aVL, and V2-V6. ST segment changes are most marked in leads V2 and V3, where the amount of J point ST elevation exceeds 5 millimeters. Inferior leads III and aVF show prominent reciprocal ST segment depression. Small Q waves have developed in leads I, aVL and V6, which probably are significant given the distribution of ST-T wave changes. Overall, the hyperacute picture of tall and peaked T waves in all chest leads with ST elevation is striking.
The history of new-onset chest discomfort in association with ECG findings in the figure strongly suggests acute occlusion of the left anterior descending coronary artery.
The clinical significance of ECG findings in the initial tracing (taken when the patient first presents for medical care) is not always apparent. This may be due to a lag time between the onset of symptoms and the resultant physiologic effect this may have on the electrocardiogram. Awareness of how short the time interval can last for evolution from a minimally abnormal tracing to one with the marked changes seen in the figure emphasizes the utility of obtaining frequent serial tracings in a patient with new-onset symptoms and a non-diagnostic ECG, until such time that the diagnosis can be clarified.
NOTE: A picture is worth a thousand words. To facilitate comparison of the ECG shown here with the minimally abnormal tracing performed just 8 minutes earlier, please visit http://tinyurl.com/KG-Blog-115 for additional details on this case.