Question 15.1

15.1.    A 65-year-old patient presents to the ED with persisting chest pain for one week. Following an acute severe episode that lasted for two hours. The 12 lead ECG taken on presentation is shown.

a.    Explain the ECG changes.    (10% marks)

b.    List the most likely diagnosis.    (5% marks)

The patient develops worsening chest pain and becomes more tachypnoeic and hypotensive. List three likely causes for this deterioration.    (15% marks)

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College answer

Aim: To allow the candidate to demonstrate expertise in the analysis of ECGs.

Key sources include: This is a repeat question from paper 2014.1 Q18. CanMEDS Medical Expert.


15.1    - The candidates who did well considered the clinical history provided, and correctly interpreted the ECG (e.g., did not confuse LBBB with RBBB).



This SAQ was a repeat of Question 18.1 from the first paper of 2014, and so the image and interpretation was also a repeat. The ECG above has been stolen shamelessly from Dr Smith's ECG Blog, where it is discussed in glorious detail. Obviously, one would find it difficult to reproduce the exact ECG which the college had in their paper, as it contained the following abnormalities:

  • Atrial fibrillation with a controlled ventricular response
  • Right Bundle Branch Block
  • Q-waves V1- V5 and which are wide
  • Left axis deviation
  • ST elevation anterior and inferior
  • ST depression in aVL

The one I have stolen is interpreted by Dr Smith in the following fashion:

There is RBBB, but without the usual rSR' in right precordial leads.  [There is some left axis deviation as well, probably a left anterior fascicular (hemi-) block.]  The initial r-wave is gone, so that there are QR-waves (diagnostic of myocardial infarction, whether old or acute).  There is ST elevation (which is never normal in RBBB).  The negative T-wave makes it very unlikely that this acute MI, but it could be either subacute or old. 

The rest of the old college answer (back when they gave you the answers) looked like this:


  •  Recent transmural anterior MI with resulting ventricular aneurysm


  • Aneurysm rupture
  • Septal rupture causing a VSD
  • Cardiac tamponade
  • Papillary muscle rupture
  • Re-infarction

 (Pulmonary embolus)