Tuesday, April 26, 2011

"Inferior" ST depression: What is the diagnosis?

This 58 year old man presented at noon with chest pain that began the previous evening and became constant less than one hour prior. 
Now there is still sinus rhythm but with 2 complexes that are PACs with aberrancy [not PVCs (thanks to VinceD for correcting me on that!)].  There is subtle ST depression in "inferior" leads II and aVF. This should always alert to ST elevation in the opposite, high lateral, leads especially aVL.  Looking at aVL, there is indeed subtle ST elevation and also in lead I.

Here is the previous ECG for comparison:
This baseline ECG is normal


Subendocardial ischemia may have ST segment depression, but it does not reliably localized to any wall.  "Inferior" ST depression is really reciprocal to high lateral ST elevation.

The chest pain resolved with nitroglycerine, the cath lab was activated, and a 99% LAD D2 (large second diagonal off the LAD) was found and stented.

Subsequently, there was no wall motion abnormality and the maximum troponin I was 1.0 ng/ml.


Here is a followup ECG 42 hours later:
ST segments have normalized.  There are now "reperfusion" T-waves (inverted) in I and aVL, verifying a high lateral MI

1) ST depression in III and aVF should be assumed to be reciprocal to high lateral ST elevation
2) This ST depression may be the most visually arresting part of the ECG




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5 comments:

  1. VinceDApril 27, 2011 at 2:56 AM

    This is subtle and of no consequence to the outcome, but about 160ms before each PVC in the first tracing there are little blips that make me believe they are actually PACs with aberrancy. The fourth beat is also a PAC, but with less aberrant conduction. Do you agree, or am I reading too much into it?
    As always, thanks for the amazing blog, I've learned so much reading both this and your book.

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  2. akroezeApril 27, 2011 at 6:00 AM

    "1) ST depression in III and aVF should be assumed to be reciprocal to high lateral ST elevation"

    I know that ST depression can be reciprocal to elevation but isn't always. Does your statement mean to imply that specifically depression in the inferior leads is more often than not reciprocal to elevation?

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  3. ChristopherApril 27, 2011 at 8:21 AM

    Talk about a subtle STEMI! The old ECGs sell it though.

    ReplyDelete
  4. Steve SmithApril 28, 2011 at 8:48 AM

    Vince, you are absolutely right! I did not look carefully. Thanks for the correction!

    ReplyDelete
  5. Steve SmithApril 28, 2011 at 8:56 AM

    Yes, when limited to "inferior" leads, it should be assumed to be reciprocal to STE in aVL. On the other hand, when there is subendocardial ischemia, ST depression is usually in V3-V6, or in BOTH III, aVF ("inferior") AND V3-V6.

    ReplyDelete

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