Friday, May 2, 2014

ST elevation and QS-waves. ECG is equivocal. Use ED Echo!!

A male in his 50's with history of CAD, Diabetes, AAA with repair, and HTN presented for chest pain.  He complained of left-sided chest pain, onset while sitting, and described it as squeezing and radiating to left arm for the past hour.  He had similar pain with an MI 2 years ago.  The pain was worse with exertion but unchanged with Nitro.  Here is his ED ECG:
There is ST elevation in V1-V3.  The Computer Read: "Anterior ST Elevation  ***Acute MI***    
What do you think?









There is not just ST elevation, but there are QS-waves in V1-V3.  QS-waves can be due to old MI or to LVH, Cardiomyopathy, or COPD.  QS-waves with ST elevation should make one think of old anterior MI with persistent ST elevation (LV aneurysm morphology), or LVH.  The voltage is not enough for LVH, so (as with yesterday's post), LV aneurysm is high on the differential diagnosis

So we should use the LV aneurysm vs. anterior STEMI rule to help differentiate:

Rule 1: The lead in V1-V4 with the highest T-wave to QRS amplitude ratio.  This lead is V3 and we get:  4.5/14 = 0.32 (less than 0.36 suggests LV aneurysm, not STEMI)

Rule 2: (sum of T-wave amplitudes in V1-V4 divided by sum of QRS amplitudes in V1-V4).  This equals 13.5/56.5 = 0.24 (a value greater than 0.22 suggests STEMI, so this value suggests STEMI)

So we have discordant results from the 2 T-wave to QRS rules!  What to do?  

ED Echo!!

Here is the ED Echo:
This is the subxiphoid view, and it shows a bulging at the apex (an LV aneurysm).  There is an echo density at the apex that is frequently found with LV aneurysm.  This is a mural thrombus and puts the patient at great risk of stroke.

Here is the Apical 4-chamber view:
Again, this shows bulging of the apex, confirming LV aneurysm.



The patient was anticoagulated for the thrombus.  He ruled out for MI with serial troponins.  Records obtained confirmed previous diagnosis of LV aneurysm with thrombus.


Lessons:

The rules for differentiating LV aneurysm from acute STEMI are not perfect, but they can be greatly aided by bedside echo.

2 comments:

  1. Great case dr. Smith! I just want to point out that the first ECHO is not parasternal view, but subxiphoid (subcostal) 4 chamber view.

    Keep these great cases coming, thank you.

    ReplyDelete
    Replies
    1. Jan, Thanks! You are absolutely right and I have changed it.
      Steve

      Delete

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