ECG of the Week - 28th May 2018 - Interpretation

This ECG is from a 68yr old male with a background of prostate carcinoma who presented with pleuritic chest pain and dysponea.

Click to enlarge

Rate:

• 102 bpm

Rhythm:

• Regular
• Sinus rhythm

Axis:

• Normal

Intervals:

• PR - Normal (~140ms)
• QRS - Normal
• QT - 330ms (QTc Bazette 405 ms)

Additional:

• ST Depression leads I, II, III, aVF, V4-6
• ST Elevation leads aVR and V1
• T wave inversion leads V1-2
• Incomplete RBBB
• Biphasic P wave lead V2

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 with textbook and the above list is an amalgamation of the figures from both Chan's ECG in Emergency Medicine and Chou's Electrocardiography in Clinical Practice.

What happened ?

The patient had a CTPA which unsurprisingly showed a main pulmonary artery PE and was treated with anticoagulation.

References / Further Reading

Life in the Fast Lane

• Pulmonary Embolism 

Textbook

• Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.