Friday, October 28, 2016

Is this STEMI? LVH? Early Repolarization?

This 60-something with diabetes presented with abdominal pain, nausea, and vomiting.

We all know that diabetics with acute MI may present like this (see this case: "I have food poisoning").

An ECG was recorded:
This was the automated interpretation:
SINUS RHYTHM
LEFT VENTRICULAR HYPERTROPHY AND ST-T CHANGE 
ST ELEVATION, CONSIDER ANTERIOR INJURY 
TYPE 2 BRUGADA PATTERN  [SADDLEBACK ST ELEVATION] 
***ACUTE MI***
Is this Acute MI?









Analysis
--There is much "anterior" (right precordial) ST elevation.
--There is also high voltage, which suggests LVH.  We know that LVH causes false positive ST elevation.
--Leads I, II, aVL, aVF and V5 and V6 have the typical LVH "hockey stick" pattern of discordant ST depression and T-wave inversion.
--However, right precordial ST elevation due to LVH should be discordant to a deep S-wave. There is no deep S-wave in V2 and V3.   So this is somewhat atypical.  
--There is also a saddleback in V2 and these are rarely due to STEMI.
--Sometimes LVH may be combined with early repolarization: high voltage and typical lateral leads on the one hand, but also right precordial leads that look like early repol with well-formed J-waves on the other hand.

Here is an extensive discussion of the LVH pseudoSTEMI phenomenon:

LVH with anterior ST Elevation. When is it anterior STEMI?



Can we use the early repolarization vs. LAD occlusion formula to help?
In the setting of LVH, this often leads to false positives, but should not lead to false negatives.  
Here it is:
Formula: (STE 60 ms after J-point in lead V3, computerized QTc-Bazett, R amplitude in V4)
Computerized QTc = 452 ms
Formula value (3, 452, 45) = 15.58
Formula value (4, 452, 45) = 16.78
These are very low values, far below 23.4, and thus very unlikely to be due to STEMI



Better yet, look for an old ECG.  Here is one from 1 week prior:
No significant difference.  This all but confirms that the first ECG is not due to STEMI.


However, you can also be fooled by previous ECGs:


Here is one from 3 months prior:
Much less STE.  This would lead you to believe the STE on the present ECG is due to STEMI
If this one had been found, one might think the presenting ECG is in fact due to STEMI.


And here is one from 1 year prior:
This is somewhat intermediate, but the computer also read STEMI.


The patient ruled out for MI.  He was, in fact, septic.  Going to the cath lab would have been detrimental to his health.

Learning Point:

Be familiar with this pattern of combined LVH/Early repolarization.  It will fool you.

Here is another example of it:











2 comments:

  1. Thank you for this example.It shows a lot. May I ask why not change value of mark 10mm to 5mm to see bether high voltage of precordial R and S waves? To estimate LV hypertrophy without computer analysis highest R and S waves using our eyes.

    ReplyDelete
    Replies
    1. Yes, that would help! But the EKG techs don't always do it, unfortunately!

      Delete

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