48 year old male CC: chest discomfort, shortness of breath

Here's an interesting 12 lead ECG that I found on the Lifenet Receiving Station at my receiving hospital. It immediately caught my eye for a couple of different reasons.

In the first place, it's an incomplete 12 lead ECG. Lead V1 is missing. This is probably the reason the GE/Marquette 12SL interpretive algorithm is giving the "Data quality prohobits interpretation" statement.

Let's move on.

There's a slight amount of wandering baseline in leads I, II, and III. However, if we ignore the first two cardiac cycles, it appears as though we have 1 mm of ST segment elevation in the inferior leads. In addition, there is a downsloping ST segment in lead aVL. That's a finding that always catches my eye!

Moving on to the precordial leads, the ST segment depression and T wave inversion in lead V2 and the flat, depressed ST segment in lead V3 are deeply concerning. This is a situation where the ability to view lead V1 would be extremely helpful, but I suspect it wouldn't look much different from lead V2.

When it comes to interpreting an abnormal finding on the 12 lead ECG, Tomas Garcia, MD is fond of saying "consider the company it keeps".

What does he mean by that?

Depending on circumstances, you might be able to dismiss an isolated abnormality or quirk on a 12 lead ECG. However, when those quirks start to multiply, and when they "fit" together (as these abnormalities do) your internal barometer should be rising with each observation.

This is a very subtle acute STEMI, but it's a STEMI none-the-less.

I did some investigating and found out that this patient ended up in the cardiac cath lab. I don't know how long it took, I don't know if the interpretive algorithm gave the ***ACUTE MI SUSPECTED*** statement when the ED performed their own 12 lead ECG, or if it was picked up by the emergency physician on duty.

However it happened, I'm glad the patient received reperfusion therapy! The reciprocal changes associated with posterior STEMI are sometimes misclassified as anterior ischemia. When the cardiac biomarkers come back positive, the patients are sometimes classified as NSTEMI.

How important is good data quality?

See also:

Anterior ischemia or posterior STEMI?

Pure (Isolated) Posterior STEMI – Not so rare, but often ignored!

3 Comments

  • Dave B says:

    This is such an important issue, and in my system, a link in the chain that sometimes is weak…
    firstly, about lead V1, i would think that if V1 looked like V2 which you suspect, that would point to posterior involvement and i would want a 15 lead… if V1 was elevated, it would point to possible RV involvement, and again i would want a 15 lead… so, either way, it would lead me to the same next step.
    about the subtle inferior STEMI, i am learning to look for this setup with the downward sloping st depression in aVL, and slight ST elevation in the inferior leads.. now, we use Zoll E series, and frankly, the tracings are not as clear as the ones i do on neighboring trucks with Lifepacks… that is issue number one. next, i am required to transmit that 12 Lead to Med Control via the rosetta device, and it comes out on their end as a fax. under the best of circumstances, there is some distortion.
    so, what happens with the subtle ecg’s is that often the subtleties that may be visible to me are not necessarily clear on the other end, where the end decision is made to activate the cath lab (in our system, providers are not allowed to activate, only the doc at med control with the 12 lead).. they are not likely to make decisions like that based on a tracing that does not clearly show the abnormality. it can be frustrating, and i hope as our STEMI system evolves that this will change.

  • Chris. says:

    Hey.

    Why the 15 lead ? Its a STEMI even without a 15. But i see your point.

    This pt should never have seen the ER, he or she should have bypassed the ER and went direct to the cathlab.

    Its always easy to be an wiseass back here in my sofa =).

    Nice case. C ya.

    /Chris, SWEDEN.

  • this is pretty subtle strip that is highly suspicious. and if it doesn’t get repeated to get a better tracing, someone should be hauled into the office.

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