Subtle Inferoposterolateral OMI, sent home!!

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.
This is diagnostic of inferoposterior OMI

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 OMI.  Most patients with missed OMI 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. 
This is diagnostic of inferoposterolateral OMI.

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.