Thursday, August 12, 2010

35 yo woman with LAD occlusion manifesting with only hyperacute Ts and inferior ST depression, also missed by computer

Click here for other cases of missed STEMI.
Click here for cases of early repolarization vs. LAD occlusion

A 35 yo woman had the sudden onset of epigastric pain, more severe and different from her usual acid-related pain. She presented ambulatory. She had an ECG ordered by the triage nurse. The patient and the ECG were placed in a far-away room.


The computerized ECG read was:

"Minimal ST depression, inferior leads" and
"ST Elev, Probable normal early repolarization pattern."

This ECG is diagnostic of STEMI: the T-waves in V2 and V3 tower over the entire QRS. As described in 3 previous cases, inferior ST depression is due to high lateral STEMI (see this post and this post):


Early repolarization always has prominent R-waves in V2-V4. This is not early repol.

Because of a variety of issues, the physician did not see this ECG immediately. Had the computer read "ischemia" or "AMI", the tech would have brought it immediately to his attention. He did not rush to see it because it was a 35 year old woman with atypical symptoms. When he did see it, he recognized STEMI immediately.

The next ECG showed anterior Q-waves. She did go to the cath lab with some delay and had an ostial LAD occlusion that was opened. She had a subsequent EF of 35%!

  • Anyone, of any age or sex can have MI.
  • Do not trust the computer.
  • You must read the ECG yourself.
  • Have a system to review all ECGs that have been recorded.

Earlier posts on early repolarization use the application of a regression equation to differentiate early repol from anterior STEMI. See this post (which also includes an example of serial ECGs, this post (which also demonstrates straightening of the ST segment, and this post (which also shows serial ECGs improving after a reperfused LAD occlusion).



Below is an old rule.  It is best now to use the equation on the sidebar:

I have also derived a simpler rule but which may not work as well in cases of very low or very high QTc:

If 2 of 3 of these are positive, then it is anterior STEMI over early repol with a sensitivity and specificity of 90%:

1) R-wave in V4 less than 13 mm
2) computerized QTc greater than 392 ms
3) ST elevation at 60 ms after the J-point greater than 2 mm
Here is another example that points out the use of serial ECGs when the diagnosis is in question:

7 comments:

  1. Dr. Smith -

    There was a similar looking ECG in a case study posted to the EKG Challenge forum at the EMS Village back in Sept 2009.

    Could you please take a look and share your thoughts?

    Tom

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  2. Yes, V2 and V3 are similar. However the case you pointed out also has quite a bit of ST elevation in other leads, and I suspect the computer would have seen this, no?

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  3. I was going to comment on the fact that the ST elevation in lead II on your case looks like pericarditis, but the hyperacute T-waves in V2 and V3 are very unusual for pericarditis. I have seen such T-waves once before in pericarditis (and published it in the pericarditis chapter of my book "The ECG in acute MI.") If pericarditis, it is very atypical, and I would assume STEMI unless proven otherwise.

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  4. should we measure st elevation not from the j point but after it by 0.06 of second ????????????

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  5. No clinical trial of reperfusion therapy has designated a method of measurement of ST elevation. Because the PR segment may be normally depressed as part of the atrial repolarization wave, and that wave extends to the J-point, then if measured at the J-point, the ST segment should be relative to the PR segment. If measured at 60 to 80 ms after the J-point, it should be relative to the TP segment.

    In any case, if you measure at 60-80 ms after the J-point, you get dramatically higher measurements, as I showed in this paper:

    Smith SW. Academic Emergency Medicine 13(4):406-412, April 2006.

    http://onlinelibrary.wiley.com/doi/10.1197/j.aem.2005.10.019/abstract

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  6. Just a question.. Is loss of R-wave amplitude incorporated into the ecg interpreting algoritm? Here there is loss of amplitude from v1 to v2. Wouldnt you say this is a strong indication for MI, and that this should be read by the machine if this was part of the algoritm, and if not, perhaps be included?!

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  7. The computer algorithms are proprietary. I do not believe they take R-wave amplitude into account. My new equation (see side bar, with online calculator) does use R-wave. In fact, I found that, when differeniating subtle LAD occlusion from early repol, the R-wave amplitude is more important than the amount of ST elevation.

    ReplyDelete