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Let me start by saying that some pulmonary embolisms(PE)’s are obvious. In those, you don’t need pulmonary embolism ECG findings to make the diagnosis. I recently was shown an ECG and asked what the patient’s diagnosis was. I asked my colleague, what the patient presented with. He replied;

“This is a 68 yo woman who presents with a sudden onset of shortness of breath. Her saturations on room air are 87%. She is afebrile and is in a new rapid atrial fibrillation. Her background history is metastatic cancer.”

My response,”She has a PE, why do I need to look at the ECG?” Correct, however it isn’t always this straightforward and in same cases, as shown in the literature, the ECG changes may be mistaken for ischaemia.

Let’s look at the ECG changes in PE

There are PE’s that are significant and those that aren’t. Most of us are walking around with PE’s and don’t know it. These are those sub segmental PE’s that the lungs clear. Perhaps then, the most common finding on ECGs is normal sinus rhythm.

Here is a list of finding on ECG in someone with a pulmonary embolism.

  1. Sinus tachycardia
  2. Supraventricular tachycardias such as SVT or PE
  3. S1Q3T3– up to 50%- but can occur in those without PE. It is a sign of COR PULMONALE(Press and Vol overload of RV). Other causes of cor pulmonale include: bronchospasm, Pneumothorax and acute lung disorders
  4. T wave Inversions in the anterior and inferior leads. The most specific finding.
  5. RBBB pattern
  6. Right axis deviation
  7. Transition point shift
  8. P-pulmonale
  9. Dominant R wave in V1, indicating right ventricular dilatation


T wave inversion Inferiorly and anteriorly- most specific

T wave inversion

Right Axis and Dominant R wave and P pulmonale


Transition Point shift

Watch the Video and come to Cardiac Bootcamp to learn about reading all critical ECGs.


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