Does the ECG help us in PE ?

The ECG in Pulmonary Embolism ultimately lacks sensitivity and specificity. Its most important role is the detection of another cause for the patients symptoms e.g. ACS or STEMI.

Some ECG features that are associated with PE are:

  • Normal ECG in 9-26% of cases
  • Sinus Tachycardia in 44-73% of cases
  • RBBB (Complete or incomplete) in 18-25% of cases
  • RAD in 16-23% of cases
  • P pulmonale in 9-33% of cases
  • Supraventricular arrhythmia in 8-33% of cases
  • Clockwise rotation in 18-30% of cases
  • T inversion Right Precordial leads in 10-46% of cases
  • S1Q3T3 in 12-25% of cases
    • S1Q3T3 whilst oft quoted as ‘the’ ECG finding in PE lacks sensitivity, specificity, and is certainly not pathognomonic of PE.

The incidence of the ECG changes in PE vary greatly between sources. further review over at

ACS vs PE

Dr Smith has already done the work for me on this one, with a great case example, and a reference to an article by Kosuge et al. Head over to Dr Smith’s blog post and read the Kosuge et al. paper.

The presence of T wave inversion in lead V1 plus lead III, as in our case here, was only seen in 1% of ACS patients versus 88% of patients with Acute Pulmonary Embolism (n=87 in ACS group, n=40 in PE group).

For a great review of the ACS vs PE issues check out the Chart Review post on ‘A Clear cut case of ACS‘