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Differential Diagnosis

  • ST-Elevation myocardial infarction (STEMI)
  • Left ventricular hypertrophy (LVH) with strain
  • Diffuse subendocardial ischemia
  • Hypokalemia
  • Supraventricular tachycardia

Diagnosis

The diagnosis in this case is diffuse subendocardial ischemia from submassive pulmonary embolism. The ECG shows a regular, narrow-complex, sinus rhythm with a rate of 138 beats per minute. There is a normal axis and normal intervals. There are diffuse ST-segment depressions in the inferolateral leads and ST-segment elevation in aVR (Figure 2).

Diffuse subendocardial ischemia
Figure 2: ST elevation in aVR (asterisks) and ST depressions in the inferolateral leads (arrows)

This pattern of diffuse ST depression with ST elevation in aVR represents global subendocardial ischemia, and can be caused by many conditions, including left main coronary artery disease or multivessel disease.1 Any condition with a supply/demand mismatch may have this pattern, including pulmonary embolism, severe anemia, hypoxia, tachydysrhythmias, and shock. Typically, the pattern on the ECG will reverse when the cause is resolved. When this electrocardiographic pattern is encountered, a broad differential should be considered. In a study of 142 ECGs with this pattern, only 27% were associated with acute coronary syndrome.2 A targeted history and physical will help to determine the cause, as well as performing adjunct testing such as labs, imaging, or bedside ultrasound.

In this case, the patient was transferred to the emergency department, where she was given adenosine for suspected supraventricular tachycardia, which did not improve her symptoms or resolve the tachycardia. Additional workup discovered a submassive pulmonary embolism. These ECG findings were due to the supply/demand mismatch in the oxygenation of the myocardium caused by her pulmonary embolism.

What to Look For

  • Global subendocardial ischemia can result from any disease process that creates a mismatch in the oxygen that the myocardium is requiring and the oxygen that the coronary arteries are supplying.
  • When diffuse ST depressions with ST elevation in aVR is encountered, consider conditions like pulmonary embolism, severe anemia, hypoxia, and shock.
  • This ECG pattern is often transient and will likely resolve when the cause is reversed.
  • Other electrocardiographic findings of pulmonary embolism include sinus tachycardia, T-wave inversions (especially in anterior and inferior leads), right axis deviation, tall P wave in lead II, and the S1Q3T3 pattern.

Pearls for Initial Management, Considerations for Transfer

  • Always consider a broad differential with this ECG pattern and allow an in-depth history and physical guide your workup and next steps.
  • Many causes of this pattern are life-threatening, and the urgent care physician should prepare for transfer.

References

  1. Kosuge M, Ebina T, Hibi K, et al. An early and simple predictor of severe left main and/or three-vessel disease in patients with nonst-segment elevation acute coronary syndrome. Am J Cardiol. 2011;107(4):495-500. doi:10.1016/j.amjcard.2010.10.005
  2. Knotts RJ, Wilson JM, Kim E, Huang HD, Birnbaum Y. Diffuse ST depression with ST elevation in aVR: Is this pattern specific for global ischemia due to left main coronary artery disease? J Electrocardiol. 2013;46(3):240-248. doi:10.1016/j.jelectrocard.2012.12.016

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65-Year-Old With Hypertension
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