ECG of the Week - 26th May 2014 - Interpretation

These ECGs are from a 60 yr old male who presented with 2 hours of chest pain. Previously fit and well. No regular medications.
These serial ECGs were performed over a 20-30 minute time frame. The first three ECGs were performed whilst chest pain was ongoing with the final ECG performed with the patient pain free.
Check out the extensive discussion on this week's case in the comments section here.

Initial ECG

Second ECG

Third ECG
Posterior lead configuration

Fourth ECG
Pain free

Rate:

• 54 bpm (3rd ECG) - 72 bpm (1st ECG)

Rhythm:

• Sinus rhythm
• Single PVC's noted in 1st and 4th ECGs

Axis:

• Inferior (+90 deg)

Intervals:

• PR - Normal (~160ms)
• QRS - Normal (100ms)
• QT - 400-440ms

Segments:
ECG 1

• ST elevation aVR (~1mm)
• ST depression leads I, II, II, aVF, V2-6 (maximal in V4)
• PR depression leads II, III, aVF
• I'm no expert on ST vectors but I absolutely trust Dr Smith and Vince DiGiulio when they tell me it's posterior :-)

ECG 2

• T waves leads II, III, aVF, V4-6 more prominent than 1st ECG
• ST elevation II, III, ?aVF (difficult to see given baseline noise)
• ST depression leads V2-4
• T wave inversion lead V2 compared with 1st ECG
• Subtle ST elevation leads V5-6 - certainly resolution of earlier ST depression

ECG 3

• Vince made a good point that in a posterior lead ECG leaving V1-3 in place rather than moving all leads is more useful but our lead configuration will not allow us to do this, hence the configuration seen in this ECG
• ST Elevation leads II, III, aVF (maximal in lead III)
• Nil progession of ST elevation leads V5-6 seen in second ECG
• T waves remain prominent in infero-lateral leads
• Nil ST elevation in posterior leads accounting for baseline - thanks Vince

ECG 4 - Pain free ECG

• T waves in infero-lateral leads much less prominent compared with second and third ECG
• ST depression in leads V2-4 resolved
• Subtle ST elevation persists in leads III, aVF - improved compared with second and third ECGs
• T wave in lead V2 now positive

Additional:

• Partial RBBB

Interpretation:

• Infero-postero-lateral acute myocardial injury

What happened ?

The patient was discussed with cardiology team and underwent emergent angiogram, which showed:
RCA - mild irregularity
LAD - 30% stenosis
OM2 - 99% occlusion --> stented
LV function preserved

Uneventful recovery and discharged after 2 day in-patient stay.

There was lots of discussion in the comments section on the utility of posterior leads and mentions of ST vectors. For more on these concepts check out the following FOAM links:

• Life in the Fast Lane - Posterior Myocardial Infarction
• Vince DiGiulio Introduces us to ST Vectors in the case from EMS 12-Lead
• Dr Smith goes through the Five Primary Patterns of Ischaemic ST Depression here
• Dr Smith shares a great case and gives you a guide on differentiating subendocardial ischaemia from the ST depression of posterior STEMI
• A paper on ST-Injury Vectors by Andersen et al from the Journal of Electrophysiology in 2010

References / Further ReadingTextbook

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