Wednesday, March 24, 2021

ECG Blog #207 (ECG MP-24) — The ECG Computer Report: Friend or Foe?


You are asked to interpret the ECG shown in Figure-1, obtained from a 52-year-old woman. Unfortunately, no additional information is available to you.

  • The Computer Report interpreted this tracing as, “Sinus rhythm; Nonspecific T wave abnormality; Abnormal ECG”.


QUESTIONS:

  • Do you agree with the computer report?
  • How would YOU interpret this ECG?
  • Is there anything to be concerned about on this ECG?

 

Figure-1: ECG obtained on a 52-year-old woman. No history available. Is there anything to be concerned about? (See text).

 

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NOTE #1: Some readers may prefer at this point to listen to the 9:00 minute ECG Audio PEARL before reading My Thoughts regarding the ECG in Figure-1. Feel free at any time to review to My Thoughts on this tracing (that appear below ECG MP-24).

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Today’s ECG Media PEARL #24 (9:00 minutes Audio) — Review on the Pros and Cons of the Computerized ECG Report.

 

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NOTE #2: Written summary of “My Take” on Optimal Use of the ECG Computer Interpretations appears below in the Addendum (in Figure-2 and Figure-3).

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COMMENT: This case brings up the issue of how best to use (or not use) the Computerized ECG Report. Like it or not — virtually all ECG systems in modern offices, clinics, urgent care centers and hospitals make use of a computerized ECG report. How best should the ECG interpretation be used?

  • NOTE: Regardless of whether you love or hate the computerized ECG interpretation — it is part of the medical record. Therefore — IF you disagree with what it says, you should cross out those computer statements that you feel are wrong.

 


MY Approach to the ECG in Figure-1:

As I’ve emphasized previously — it is always challenging when you are given a tracing to interpret without the benefit of any history. This is the situation in today’s case. I would recommend proceeding as follows:

  • PEARL #1 — Do not look at the computer report until after you have completely interpreted the ECG in Figure-1. (My rational for emphasizing this point is explained in full in the above Audio Pearl #24).
  • The rhythm in Figure-1 is regular at just under 100/minute. The QRS complex is narrow in all leads. P waves are present and upright in lead II, with a constant and normal PR interval — so the rhythm is sinus at a relatively fast rate.
  • All intervals (PR, QRS, QTc) and the axis are normal.
  • There is no chamber enlargement. (NOTE: I did not call LAA = Left Atrial Abnormality — because the negative component to the P wave in lead V1 is not deep — and I think the reason the P wave looks “notched” in inferior leads is the baseline artifact).
  • Several leads show some fine baseline artifact. This makes it difficult to appreciate if there is (or is not) a QS for the very small-amplitude complex in lead III. Other than this — there are no Q waves.
  • R wave progression is fairly normal, albeit transition (where the R wave becomes taller than the S wave is deep) is slightly delayed until lead V4-to-V5. 
  • NONE of the above descriptive findings are of concern. However, assessment of ST-T wave appearance for the ECG in Figure-1 is of concern (See below).

 

Assessment of ST-T waves:

  • Looking at all 3 inferior leads in Figure-1 together — raises concern that the T waves (especially in leads III and aVF) may be hyperacute. 
  • PEARL #2: The "definition" as to what constitutes a "hyperacute" T wave is sometimes admittedly elusive, and dependent on interpreter experience + the clinical context (See ECG Blog #193 for full discussion of this subject). That said — Consider the possibility of “hyperacute” T waves when you see T waves that are disproportionately tall and/or fatter-at-their-peak or wider-at-their-base than should be expected given R wave and S wave amplitude in that lead. The more leads in a given lead area that show hyperacute changes — the greater the concern for acute OMI (Occlusion-based MI).
  • In Figure-1 — QRS amplitude in leads III and aVF is admittedly tiny, and this makes it that much more difficult to assess what constitutes “larger-than-expected”. That said — T wave amplitude in lead III actually exceeds QRS amplitude in this lead — and the T wave is clearly more “voluminous” than one would normally expect. While not as obvious in lead aVF — the T wave in this 2nd inferior lead also looks more “voluminous” than might be expected. That said — the 3rd inferior lead ( = lead II) does not look overly abnormal.
  • PEARL #3: Despite a lack of ST elevation in lead III, and a lack of J-point ST depression in lead aVL — there does appear to be that “magical” mirror-image opposite picture for the shape of reciprocal changes for the T waves in leads III and aVF (See ECG Blog #184 for full discussion of this subject). This finding should significantly increase your concern about possible ongoing or recent OMI.
  • There is subtle-but-real T wave inversion in lead I. Given the absence of voltage criteria for LVH — I felt this subtle, shallow T inversion in lead I supports concern about reciprocal high-lateral ST depression.
  • There is some nonspecific ST-T wave flattening in most of the chest leads — but this does not look acute.

 

BOTTOM LINE: The KEY point is that we need some History in order to know what to do with this tracing. 

  • Finding a prior ECG on this patient could prove invaluable — because it is possible that the ECG changes we see in Figure-1 are old.
  • In the absence of a prior ECG on this patient — IF the clinical history suggested new or recent symptoms for possible coronary disease — then the ECG in Figure-1 could represent an acute or recent event!
  • An acute or recent event would be far less likely if this patient had no new or recent symptoms — which places the onus on us to find out the clinical history!
  • Although the computer did recognize that the ECG in Figure-1 is abnormal and shows “T wave abnormality” — the computer failed to recognize the possibility of a recent or acute ongoing cardiac event. Hopefully the clinicians caring for this patient did not depend solely on the computer interpretation at the time they decided on management of this patient. 

 

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Relevant ECG Blog Posts to Today’s Case:

  • ECG Blog #193 — Discusses the concept of using the term, “OMI” ( = Occlusion-based MI) instead of STEMI — and — reviews the ECG findings to look for when your patient with chest discomfort does not manifest frank STEMI-criteria ST elevation on ECG.
  • ECG Blog #184 — Reviews the “magical” mirror-image OMI relationship to look for between leads III and aVL.

 

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ADDENDUM (3/23/2021): In the following 2 Figures — I review “My Take” on the Pros and Cons of the Computerized ECG Report.

 

 

Figure-2: “My Take” on the Pros & Cons of Computerized ECG Interpretations (Please listen to my 9-minute ECG Audio Pearl above, in this post = ECG MP-24).


 

Figure-3: Example of hyperacute T waves missed by the Computer Report.




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