Friday, December 9, 2011

Subtle Inferoposterolateral STEMI

This ECG comes from Tom Bouthillet, who is devoted to good STEMI care, runs the EMS12lead ECG site, and who has also produced an outstanding iPhone/iPad/Android 12-lead ECG challenge App for learning to recognize subtle STEMI and to differentiate STEMIs and look alikes.

Case 1. This was a 70 year old woman who had chest pain while exercising the day before, then developed chest pain on the day of the ECG and called 911.  Here was her prehospital ECG.
There is very subtle ST elevation in inferior leads, with hyperacute T-waves, with subtle reciprocal ST depression in I and aVL, and T-wave inversion in aVL.  There is minimal ST depression in V2.  T-waves in V5 and V6 are perhaps a bit hyperacute, too.
For contrast, let's look at limb leads and V4-V6 side by side with a normal ECG:
Here the contrast in T-wave size is obvious. Normal has a wide range, and not all normal inferior T-waves are this small.  But the ones on the left are clearly too large.
Here the contrast in T-wave size is obvious. Normal has a wide range, and not all normal V4-V6 T-waves are this small.  But the ones on the left appear too large.

The medics did not see this.  The computer did not see this.  The patient was brought to the ED and discharged after ED evaluation.  Unfortunately, we do not have any ED data on this case.  What did the ED ECG look like?  Was there an old one for comparison?  It is hard to imagine that this was a baseline ECG.

I suspect this was a missed STEMI.  Most patients with missed STEMI at least get admitted to the hospital for a rule out.

Case 2. Here is a similar case in which all the data is available:

A 65 year old woman with no previous cardiac history presented with 2 hours of typical chest pain.

There are inferior hyperacute T-waves, some minimal ST depression in V2, and lateral hyperacute T-waves.  There is 0.5 mm of ST depression in aVL.  In my opinion, this is diagnostic of inferoposterolateral MI.
Here is the patient's previous ECG:

It is not entirely normal, but there are no large T-waves anywhere.  This establishes that the presentation ECGs findings are new.

These findings were also not recognized.  The patient was admitted to the CCU.  Troponin I peaked at 63 ng/ml 14 hours later.  Angiography showed an occluded dominant left circumflex.  Echo showed an infero-postero-lateral wall motion abnormality and EF of 55%.

Learning points: Scrutinize the ECG for T-wave size and morphology, especially in reciprocal leads III and aVL.


  1. mind blowing
    can i plz ask where are some normal ecg
    or could you plz start from basic normal ecg
    will b good for new learnrs

  2. I'm sorry that one weakness of my site is that it is not appropriate for those beginning to learn to interpret the ECG; the ECGs are usually quite difficult. This seems to be a good place to start:

  3. Tom (mentioned at the top of this article) has a LOT of "back to basics" articles on his web site if you go back to the first posts. It is what really got me going in ECG interpretation beyond "is there elevation".

  4. The problem is (in my area) that practitioners don't do the ECG and sometimes (quite often), precordial leads are in a wrong place (for instance, V1 can be V3R) and you can't rely on subtle findings based on specific positions.

  5. Thanks for the comment, and good point, but I don't think these findings would be produced by malposition of leads, however.

  6. Dr Smith,
    When you see T waves that you think may be hyperacute, how will you convince yourself one way or another?

    Do you find there is a correlation between the height of the QRS complexes and the T wave amplitude?, or is more a case of just eyeballing it and looking for reciprocal changes?

  7. 1. Size ( both height and width or bulkiness), and relative to r- wave or QRS height
    2. Serial ECG'S if you suspect but cannot be certain
    3. Seek old ECG, as they did not do in the second case
    4. Stat echo or angiogram if still uncertain


    Steve Smith

  8. Marvelous piece of information you have shared. I really like it. Thanks for sharing.



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