By Ken Grauer, MD

Professor Emeritus in Family Medicine, College of Medicine, University of Florida

Dr. Grauer reports no financial relationships relevant to this field of study.

A previously healthy 19-year-old man presented to the ED following a syncopal episode. His initial ECG is shown in the figure below. Are the ST-T wave abnormalities seen in this tracing the result of early repolarization? Or is this likely to represent acute pericarditis? A CT angiogram was performed while the patient was in the ED. It was normal. Does this alter your diagnostic considerations?

We interpret the ECG in the figure as showing sinus arrhythmia (normal intervals and axis), low voltage in the limb leads, and no chamber enlargement. An rSr’ complex is present in lead III. Tiny Q waves are seen in leads I, aVL, V5, and V6. R wave progression is normal, with transition occurring between leads V3 to V4. The tracing is remarkable for its ST-T wave changes. T waves are markedly peaked in multiple leads. Additionally, multiple leads show upward-sloping (i.e., “smiley” configuration) ST segment elevation. There is no reciprocal ST depression.

ST segment elevation in multiple leads with T wave peaking as seen here should bring to mind several diagnostic considerations. These include acute pericarditis, hyperkalemia, ST segment elevation myocardial infarction (i.e., an acute STEMI), a repolarization variant, or acute myocarditis. Or is it something else?

The normal CT angiogram plus initial laboratory work ruled out the possibility of the above entities. Serum potassium was normal. Acute pericarditis usually does not present with syncope, and T waves clearly are more peaked in this tracing than usually are seen with acute pericarditis. Acute infarction would seem unlikely given the normal CT angiogram, the lack of chest pain in the history, and the lack of reciprocal ST depression on ECG. The history also does not suggest acute myocarditis. Finally, the amount of ST elevation and the degree of T wave peaking seen here clearly are more marked than generally is seen with a simple repolarization variant.

Cardiac catheterization revealed clean coronary arteries and a myocardial bridge in the mid-portion of the left anterior descending coronary artery. While not a common cause of acute cardiac symptoms, it is important to be aware of the possibility of myocardial bridging, especially when symptoms arise in a younger adult not expected to have coronary disease. The diagnosis in this case would have been missed had cardiac catheterization not been performed.

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