Acute Myocardial Infarction, or Acute Pericarditis?
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.
The ECG in the figure below was obtained from a middle-aged man. Is this tracing most consistent with acute myocardial infarction or acute pericarditis?
The rhythm is slow and regular (sinus bradycardia). The PR interval is normal, and the QRS complex is narrow. However, the QT interval clearly is prolonged. The frontal plane axis is normal. There is no chamber enlargement. The most remarkable findings on this tracing are the prominent J-point notching (best seen in leads V3, V4, and V5) and upward-sloping ST segment elevation in the inferior leads (and in most of the chest leads).
The described ECG findings need to be interpreted in light of the clinical situation. I intentionally omitted the history in this case. It turns out this middle-aged man was found outside during the winter months. His core temperature on arrival in the hospital was 83°F. This ECG demonstrates typical findings of hypothermia. These include bradycardia, QTc prolongation, prominent J-point notching (Osborn waves), and upward-sloping ST elevation in several leads. Considering this constellation of findings in association with the markedly reduced core temperature, the chances are that all ECG findings are the result of hypothermia. The lack of significant Q waves, lack of any reciprocal ST depression, and the prominent J-point notching all suggest this may not be an acute infarction. Acute pericarditis is far less common than is generally appreciated. Usually, it is not associated with bradycardia, a long QTc, or such prominent J waves.
Even if this patient did suffer superimposed acute infarction (in addition to hypothermia), the highest priority in treatment still would be treating the hypothermia. After core temperature normalizes, one can repeat the ECG and question a much more alert patient to determine if there was any chest pain. Chances are that virtually all the ECG findings discussed in this article will have normalized.
For more information about and further discussion on this case, please click here.
The lack of significant Q waves, lack of any reciprocal ST depression, and the prominent J-point notching in the figure all suggest this may not be an acute infarction.
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