Thursday, May 1, 2014

ST Elevation: is it due to old MI (LV aneurysm) or to acute STEMI?

A middle aged male was resuscitated from cardiac arrest (ventricular fibrillation).  Here is his initial ECG.  He was hypotensive.
Besides the Atrial Fibrillation, what do you think?











There is a slightly wide QRS, at 115 ms (by the computer).   It is not quite a bundle branch block, but rather a nonspecific intraventricular conduction delay (IVCD).  There are QS-waves in V3 and V4, and a QR-wave in V6.   There is some minimal ST elevation in V4 and V5, but in V4 it is not excessively discordant (if we can apply modified Sgarbossa rules even in nonspecific intraventricular conduction delay) and in V5 it is not concordant to the majority of the QRS, nor is it excessively discordant.

He underwent synchronized cardioversion into sinus rhythm, after which his blood pressure normalized.   Then had the following ECG recorded:
What do you think?


Analysis

The QRS is 116 ms.  It looks like IVCD with left ventricular aneurysm morphology.  Is it:
1. Simply persistent ST elevation after old MI (LV aneurysm morphology)?  
2. Acute STEMI?  
3. Subacute STEMI?  
4. LV aneurysm with acute STEMI superimposed?  

This is not at all an academic question: Both LV aneurysm and acute STEMI can cause VF arrest.

Hint: The ST elevation in V4 and V5, and the T-wave amplitude, appear to be too great for simple persistent ST elevation.


Is there a way to differentiate anterior LV aneurysm morphology from acute anterior STEMI?

Yes.  We have derived and validated (abstract in press) two similar formulas with moderate accuracy (85-87%), with sensitivity for acute STEM of about 90% and specificity of about 70%.   We also showed that they are more specific than another rule that uses QRS fragmentation.  The two formulas rely on the fact that acute STEMI not only has ST elevation, but has a prominent T-wave.

Rule 1: if there is any T-wave to QRS amplitude ratio among leads V1-V4 that is greater than 0.36, then it is likely to be acute STEMI.

Rule 2: if the sum of T-wave amplitudes in V1-V4 divided by the sum of QRS amplitudes in V1-V4 is greater than 0.22, then it is likely to be STEMI, not LVA

Outcome

The patient was cooled and taken to the cath lab.  There, a long acute mid-LAD 95% lesion with thrombus and low flow was seen and opened and stented.  There was also complex 3-vessel disease but the acute lesion was in the LAD.

Subsequently, records from another hospital revealed that he had a history of ischemic cardiomyopathy and of LV aneurysm with LV thrombus.  The thrombus had since resolved.

Here is the post-cath ECG:
The T-wave amplitude is diminished, and the ST elevation is also diminished. 
Now apply the rules:
Rule 1: V2 has 16.5/18.5 = 0.35, which is less than 0.36
Rule 2: (1.5 + 6.5 + 4 + 1) divided by (14.5 + 21.5 + 20.5 + 5 = 13/61.5 = 0.21 which is less than 0.22

The ECG thus supports the diagnosis of LV aneurysm now that the acute STEMI is resolved.


Formal echocardiogram confirmed dyskinesis (aneurysm) of the distal septum and apex.  EF was 16%.  Peak troponin I was 22 ng/mL.

Diagnosis:

LV aneurysm with superimposed acute STEMI.  

18 comments:

  1. Dear Steven,

    Besides, there is a late T-wave inversion in both V4 and V5 leads... Not usual in LV-aneurysm

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    Replies
    1. Nicholas, I would disagree with that. Late T-wave inversion is very common in LV aneurysm.
      See here: http://hqmeded-ecg.blogspot.com/2008/11/ecg-review-2_10.html
      and here: http://hqmeded-ecg.blogspot.com/2008/11/is-this-wellens-syndrome.html

      It is as prevalent as an upright T-wave.

      I have many more.

      Steve

      Delete
    2. thank you dr steve for such anice and amazing case

      Delete
  2. Thanks for your comment. Because of the T-wave inversion and too high STE, I would refer to Cath-lab. My question: is there other differentials between aneurysm and STEMI with aneurysme than the formula?

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    Replies
    1. I asked Nicolas to clarify, and this was his question:

      I should say, you use the formula, but without, do you have other signs to get the right diagnosis?

      Yes. The diagnosis of anterior LVA should be suspected in the setting of QS-waves or very poor R-waves. Without the Q-waves, the consideration is really not even present and one should not attempt to use this formula.

      Thanks for the great question.

      Steve

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  3. I see the STE in lead V5 a bit unusual, this maybe the hint that clues me into thinking this is LVA on acute STEMI
    By the way, I think u mean
    Rule 1 : Any T/QRS ratio in V1-V4 > 0.36
    Rule 2 : Sum of T / Sum of QRS in V1-V4 > 0.22
    Which supports the dx of acute STEMI in the setting of LVA

    ReplyDelete
    Replies
    1. Thank you for picking that up! That was a terrible misprint.

      Delete
    2. Dr Smith when u say " The ST elevation in V4 and V5, and the T-wave amplitude, appear to be too great for simple persistent ST elevation ", how did you really eye-balled it?

      Delete
    3. Ryan, The reason I have a numeric rule is that is the only way I know of to communicate my perception that the ST elevation and T-wave amplitudes are too great. I don't know of any other way to tell you how I "eyeballed" it!
      Steve

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  4. i am confused, can there be ischemia in already necrotized tissue? He had acute 95% mid LAD stenosis and history of LV aneurysm.
    My opinion this was not u true STEMI. He had significant mid LAD stenosis preveiosly vhich lead to LV aneurysm or it was just hibernating myocardium. And now rupture occurs that does not completly occludes the culprit vessel.
    And tachycardia (109/min) contributes to ST elevation that is seen inV4-V6, but also in other lead where are q waves like in lead III or aVF.
    Like in stress testing you may see STelevations in leads where is patological q wave.

    ReplyDelete
    Replies
    1. Good question.

      Even in LV aneurysm, there is still plenty of viable myocardium. Although the artery was open at cath, it was not necessarily open at the time of the ECG. Also, even though open, it had slow flow, inadequate flow. The proof is in the troponin elevation to peak of 22: there was enough myocardium to produce a large troponin leak with the infarct. Although you are right that tachycardia can exaggerate ST elevation, the final ECG shows almost no ST elevation to be exaggerated. This is definitely new STEMI superimposed on old LV aneurysm.
      Steve Smith

      Delete
  5. is there a reason you used different values for the QRS amplitude in V2 in rule 1 vs 2 (18.5, 21.5)

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    Replies
    1. probably just forgot what I was doing and measured different complexes (mistake). won't make a difference.

      Delete
  6. why notch in ascending part of QRS complex in V3 ?

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    Replies
    1. It is like a Q-wave in the midst of the S-wave, loss of anterior forces for a moment because of an area of infarct that has no anterior forces.

      Delete
  7. Very NICE illustrative case on a concept that I know you have been working on for some time now! I think the most insightful comment is in your answer to Ryan Tee’s question above = the reason for the helpful numeric rule is to facilitate communication of your near-instant perception that the ST elevation and T wave amplitudes are more-than-they-should-be for the QRS in the post-conversion ECG. Validation of your data with your soon-to-be-published work adds credibility.

    QUESTION: I agree that the 2nd ECG (post-cardioversion) look abnormal (and satisfies criteria in your equations). My question is if this patient was not cardioverted and the only tracing you had was the 1st ECG — How certain would you be that there was a new acute STEMI in addition to suspected LV aneurysm (ie, this tracing doesn’t look all that abnormal except for slightly-more-than-expected ST elevation in V5 … ).

    THANKS again for your insights!

    ReplyDelete
    Replies
    1. Ken,
      First, it is now validated and published: http://www.ajemjournal.com/article/S0735-6757(15)00190-4/abstract
      Second, I would not be at all certain if the patient were still tachycardic, as tachycardia often exaggerates T-wave amplitude. Do you agree?
      Steve

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  8. Congratulations on publication of this work! Yes, we both agree that ST-T wave morphology becomes more difficult to assess with tachycardia! THANKS again for posting this case.

    ReplyDelete

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