Saturday, September 30, 2017

30 yo woman with chest pain and a "normal ECG" by the computer, this one prehospital

This was sent by paramedics in the Northwest Ambulance Service in the UK.  James Alameddine credits his partner, Gary Wilson.

Case

A 30 year old woman complained of chest pain and called 911.

She had a prehospital 12-lead ECG recorded:
As you can see, the computer interpretation is "normal"
What do you think?




















This very perceptive medic noticed that the T-wave in V4 is far too tall for the QRS.  Very abnormal.  But computers are not programmed to find all abnormalities, including many that are dangerous.  This is this one.

How about ST Elevation?

There is (as the computer measures -- at the side) more than 1 mm of STE in V2 and V3, but not the 1.5 mm that would trigger "STEMI" in a woman.

Thus, you have to decide if this STE is due to normal variant or due to ischemia.  Normal Variant ST Elevation always has good R-wave progression, and here the R-wave in V4 is only 3 mm.

If we use the 3-variable formula, with STE60V3 = 2 mm, QTc = 413, and RAV4 = 3, the value returns at 25.8 which is clearly diagnostic of LAD occlusion.

The 4-variable formula which includes the QRS amplitude in V2 turns out to be: 20.6 (most accurate cutoff is 18.2), so both formulas predict LAD occlusion.

The T-waves in V4-V6 should never be taller than the R-wave and should even be far less tall.

They should look like this:


Here are some more examples of hyperacute T-waves in V4-V6:


An elderly man with severe chest pressure......



This one was also called "normal" by the computer (but in this case, also by the physician)


Case continued:

Because of this hyperacute T-wave, the medic continued to record serial ECGs over the next 20 minutes:
Now there is subtle ST depression in lead III, seen by the computer


Clear ST Elevation in I, aVL, V4-V6, with reciprocal ST depression in II, III, aVF



Obvious Proximal LAD occlusion

The medics activated the cath lab and the patient went straight to the cath lab and had an LAD occlusion opened and stented.

The medics were unable to get any other information such as troponins or echo.

Here are more cases of "normal" ECGs, posted on September 28:

Just a few cases that the computer called "normal"


Question: How would you like it if there was a policy that patients with "normal" ECGs do not need it to be reviewed by the physician?

This young woman with chest pain would be listed as "very low risk" and would sit in triage for many hours until she arrests or loses half of her myocardium.


7 comments:

  1. Great ECG. Hope to see a validation from Smith+V2 rule! A question frequently asked by EP working far away from cath labs: would you lyse such patient? No data about this, so I answer "no". Is there any place to think about lysing those patients in some situation? Cheers.

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    Replies
    1. Alain, I also answer No!, and many say that they could never get their interventionalist to act on such a case. I answer that the reponse to such an ECG is not to activate the cath lab, but to do intensive evaluation: serial ECGs and contrast Echo. Some may turn out to be false positives. I give a talk on "The False STEMI-non-STEMI Dichotomy." The other false dichotomy is 1) Activate cath lab or 2) don't activate (also: 1) give lytics or 2) don't give lytics. There is a middle ground: evaluate intensively. don't simply "rule out MI" with biomarkers: they will only turn positive when too late.
      Thanks for the great comment!
      I'm sitting next to Pierre now. He will go back to Paris today.
      Steve

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  2. The T wave in Lead 3 is also quite tall (hyperacute).. Any comments on that?
    Thank you...

    ReplyDelete
    Replies
    1. MG,
      I agree but that is very subtle and I'm not certain how specific it would be.
      Steve

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  3. GREAT case with MANY important “take-home” points! Thank you to James Alameddine & Gary Wilson from the UK for this contribution! i) As per Dr. Smith — the T wave in lead V4 is not “normal”. Not only is it “too tall” for the QRS — but it is “too fat” at its peak (ie, the T in V4 is “disproportionate” to the QRS complex in this lead). ii) Despite her young age of 30, this patient has new chest pain. This means that one NEEDS to assess the rest of the ECG with extra care given the clear finding that the ST-T wave in lead V4 is not normal. iii) I favor the concept of “neighboring leads”. This means that whenever you see a potential ECG abnormality in one lead — Look extra carefully at the leads that view neighboring parts of the heart. In this case, while I would accept that the ST-T wave in lead V5 is not abnormal — in the context of the abnormal T wave in lead V4, the T wave in lead V3 here DOES also look suspicious. That is, this T in V3 looks a bit taller and broader at its peak than I would normally expect. Admittedly, if I only saw lead V3 — I would not be convinced of significant abnormality. But — in the CONTEXT of abnormal ST-T wave in lead V4 in a patient with new chest pain, I suspect lead V3 is showing a similar potentially acute phenomenon as we suspect is occurring in lead V4. iv) The inferior leads in this tracing are NOT “normal”. The abnormalities are subtle, and not helped by the variation of the baseline in leads III and aVF. Again, looked at in isolation — I would not be expecting an acute event from simple assessment of leads II,III,aVF. But in the CONTEXT of a patient wth chest pain + the definitely abnormal T wave in V4 + the suspicious T wave in V3 — then the ST segment flattening in leads III and aVF is NOT “normal”, and may represent early reciprocal change. BOTTOM LINE: I would in no way be certain from this single tracing that this patient was about to evolve an acute anterior STEMI. But the astute clinician should follow the laudatory example of James Alameddine and Gary Wilson by heightening their index of suspicion based on this tracing, and then confirming this over ensuing minutes by serial tracings. FINAL Point v) One should not get “stuck” on a “millimeter definition” for what does or does not constitute an acute stemi. Instead, morphology and clinical context are far MORE important than the number of millimeters of st elevation when one’s goal is to achieve optimal clinical ECG interpretation.

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  4. Great post... Thank you Dr.Smith and Dr.Ken...
    If 1st ECG was taken in ER,and we had picked up on those subtle changes, would an early ECHO(RWMA) decide if patient needs urgent cath? OR we should wait for serial ECGs to show definite STEMI/positive tropT?

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    Replies
    1. Early echo would have shown a regional wall motion abnormality

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