Pulmonary Embolism - ECG

Acute pulmonary embolism can manifest in different ways. The ECG diagnostic is not easy as the ECG may be totally normal, but sometimes we may find some specific changes that could be highly suspicious.

  1. There is often present sinus tachycardia or atrial fibrillation
  2. There is often present RBBB
  3. We often find the “S1Q3T3 phenomenon”, i.e. deep S in lead I + deep Q and negative T wave in lead III
  4. We often find negative T waves in chest leads (usually in a more massive embolism)


Pulmonary Embolism - ECGThis is a typical ECG of a patient with the acute pulmonary embolism. We see tachycardia, the S1Q3T3 pattern (blue) and RBBB in V1 (red).

Conclusion: We can not diagnose the embolism only due to ECG. It is important to follow the clinical signs and patient’s medical history. When there is a suspicion, we can confirm it by a lung scintigraphy or CT-angiography.


Jiri Stefanek, MD  Author of texts: Jiri Stefanek, MD
 Contact: jiri.stefanek@seznam.cz
 Sources: basic text sources