Wednesday, September 29, 2021

Massive ST Elevation in a 38 year old with Syncope

This ECG was texted by a former resident with the words "38 year old, syncope while urinating.  Negative troponin."

What do you think?

There is massive ST Elevation of 5 mm (at the J-point, relative to the PQ junction) in lead V2.  There is 3 mm in lead V1 and 2.5 in lead V3.  

But there is also 57 mm QRS in V2 and a 19 mm R-wave in V4.  The QT interval is not very long.

My response was this: "I have seen this pattern before and it is very unlikely to be OMI."  I did not know what "troponin negative" referred to [single troponin?  below the level of detection?  2 serially negative trops below the LoD?  Or below the 99th percentile.]  Nevertheless, I added: "And if you now have negative serial troponins, you have proven it."

Clearly the provider who sent this to me strongly suspected it was a false positive (as he/she did not act on it except to measure troponin), and I don't know if that is due to low pretest probability, patient appearance/exam, or knowledge of this PseudoSTEMI pattern.

Can we use the formula?

12 Example Cases of Use of 3- and 4-variable formulas, plus Simplified Formula, to differentiate normal STE from subtle LAD occlusion

First, we must answer all these questions in the negative:

1. Is there BBB?

2. Is there T-wave inversion?

3. Is the ST segment more than 5 mm in any lead (here it = 5 mm)

4. Is there terminal QRS distortion?

5. Do any of the leads with ST Elevation have a convex ST segment (here they are straight, which is also worrisome, but they are not convex)

6. Is there significant ST depression in inferior leads

7. Is there STD in V2-V6?

8. Are the pathologic Q-waves in any of V2-V4?

So, yes, we can use it.

If we use the 4-Variable formula, we get: corrected QT interval of 400 msec, QRS V2 of 57 mm, R wave in V4 of 18.5 mm, and ST Elevation at 60 ms after the J point in lead V3 = 4.5 mm.

This gives a very low value of 12.0.  

No result, no matter how low, absolutely rules out LAD occlusion, and if your suspicion is high, then go with your clinical impression.  The formula is mostly to be used when you DON'T think there is OMI.  It is not to dissuade you from OMI!!

But this is a case of syncope, not chest pain.  So the pretest probability is much lower.  And I'm telling you to memorize this morphology as one that is occasionally seen in non-ischemic ECGs.

In such a case, it is OK to delay just a few minutes to find an old ECG, or establish absence of wall motion abnormality.

It is also OK to have a false positive cath lab activation.

This patient would not stay for further workup, so whether there was structural abnormality or not is uncertain. But I can say that I have seen normal variants with this appearance.

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