Thursday, July 16, 2015

Terminal QRS Distortion: Diagnostic of LAD Occlusion. Or is it Pericarditis?

A middle-aged woman presented with what is described as a burning feeling in her chest which the physician said was "very atypical."  It did occur during exercise and radiated to both wrists.

Here is the first ECG:
Sinus rhythm.  
Computerized QTc is 437.  
There is some ST Elevation in II and aVF but without reciprocal ST depression in aVL.  
Precordial leads also have ST Elevation:  Is this normal variant or is it Ischemic ST Elevation?  There is upward concavity in all leads, suggesting normality. But upward concavity is seen in all of leads V2-V6 in almost 50% of LAD occlusion.  There is no ST depression, Q-waves, or T-wave inversion.
The first impression of the clinicians was "pericarditis" because of the diffuse ST elevation.

The computer algorithm might say: "Diffuse ST elevation, consider pericarditis, early repolarization, or myocardial infarction." I don't know what it actually said.

Early repol vs. LAD occlusion

Should we use the LAD-Early Repol calculator?
If you did, and it was negative, it would likely be a false negative.  Why?
There is Terminal QRS distortion in V3, which is not a finding of normal variant ST elevation.
What is Terminal QRS distortion?
Terminal QRS distortion is the absence of both an S-wave or a J-wave in either V2 or V3.  It is not seen in early repolarization, or is very rare.  In the right clinical context, and in the presence of non-diagnostic ST elevation, it is highly suspicious for coronary occlusion.

They did apply the formula, using these measurements: 1.5 mm for STE at 60 ms after the J-point in lead V3, QTc of 437, and R-wave amplitude in V4 of 13.  (I would have used 2, 437, 14)

Their numbers resulted in 23.34 (very close to 23.4, but technically negative.  I recommend that anything above 22.0 be investigated further)

My measurements would have resulted in 23.6, also very close but positive.

Pericarditis vs. LAD occlusion

I always say "You diagnose pericarditis at your (and your patient's) peril." 

Why is this not pericarditis:
1. ST vector: The ST vector in pericarditis should be lateral and inferior and only slightly anterior.  The vector here is towards V3.
2. Large T-waves: in pericarditis, the ST elevation is much more pronounced than the T-wave.  Here the T-wave is more pronounced, hyperactute.
3. No diagnostic PR depression.
4. Notice there is a Spodick's sign in V3-V5. But this is a worthless sign (see this recent post).

They recorded 2 more ECGs at unknown intervals:

2nd:
Perhaps some increase in STE



3rd:
There is slightly increasing ST Elevation



















Fortunately, the troponin came back slightly elevated, and fortunately they did not not attribute that elevation to myocarditis.

The patient was taken to angiography and found to have a 99% thrombotic LAD occlusion.




7 comments:

  1. Steve -
    Is QRS an independent predictor of occlusion, beyond what we already see here? I.e., if we didn't have a large T-wave, small R, and a straight ST in V3, would QRS distortion be as useful?
    Brooks

    ReplyDelete
    Replies
    1. Brooks,
      Yes. there are cases in which the only finding to indicate MI is Terminal QRS distortion.
      See this case: http://hqmeded-ecg.blogspot.com/2013/10/terminal-qrs-distortion-due-to-lad.html
      The most important point for me is that it is very unusual, or maybe even always absent, in early repolarization.
      Steve

      Delete
  2. Great case!

    I suspect the latter two ECGs were taken in very close proximity to the 1st, as the T's are still upright (LAD still closed) yet there is little in the way of natural evolutionary transition from tall R waves to QS waves.

    ReplyDelete
    Replies
    1. Sam, yes they were not days later, but they were hours later. There was a significant delay to angio.
      Steve

      Delete
  3. Thanks for sharing this great example.

    I was re-reviewing your marvellous book and happened to Case 7-4. May be you would consider to share it here for comparison. It is a tough one because of precordial derivations. It has ST vector directed to V2 and terminal QRS distortion in V3, similar to this case. Limb leads have less T voltage and more pericarditis look but if you kindly consider comparing it with this one I would really appreciate it.

    Thanks

    ReplyDelete
    Replies
    1. Emre,
      good pickup! This does not change the thought that when the DDx is between MI and Early Repol, terminal QRS distortion is very good for MI, because in this case, early repol was not part of the differential.
      However, it does suggest that pericarditis can have terminal QRSD.
      On the other hand, this ECG was presumed to be pericarditis, and I am pretty sure it is, but I don't believe there is angiographic or troponin proof that it was not MI.
      Steve

      Delete

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