Thursday, November 19, 2020

Anterior ST Elevation and a Finding that was Overlooked


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MY Comment by KEN GRAUER, MD (11/19/2020):

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I’d like to revisit one of Dr. Smith’s ECG Blog posts from 2012 for 2 Reasons:

  • Reason #1: It highlights the challenge of assessing anterior ST elevation in a certain type of patient.
  • Reason #2: There is one more easy-to-overlook but important finding on the ECG that was not initially detected.

TAKE a LOOK at the ECG in Figure-1. This is the initial tracing from this patient who presented to the ED with new chest pain and dyspnea.

  • There is ST elevation in leads V1-thru-V3 of ECG #1, attaining 3-4 of J-point ST elevation in lead V3.
  • QUESTION #1: Given the history (ie, new-onset chest pain) — Should the cath lab be activated? IF not — WHY not?
  • QUESTION #2: What other important finding in the limb leads should be recognized?


Figure-1: The initial ECG in the case from our February 8, 2012 post in Dr. Smith’s ECG Blog (See text).



ANSWER to QUESTION #1: As discussed by Dr. Smith back in 2012 (and reinforced many times in the 8 years since on this Blog) — the reason not to activate the cath lab based on the ECG shown in Figure-1 — is that this ECG is almost literally screaming, “The patient has LVH!"

  • QRS amplitude is dramatically increased in virtually all chest leads in ECG #1 (ie, the S in lead V2 ~23 mm; the S in lead V3 is well over 20 mm [cut off at the bottom of the paper]; the S in lead V4 ~21 mm; the R in lead V5 ~15 mm). As per the Table in Figure 3 (that I have placed in the Addendum below)  multiple voltage criteria for LVH are satisfied in ECG #1.
  • In addition — both anterior and lateral leads in ECG #1 manifest ST-T wave changes typical for LV “Strain”. Among many discussions in this Blog about the “anterior lead STEMI-mimic of LVH — the June 20, 2020 post probably illustrates this phenomenon best. In My Comment (at the bottom of the page at this June 20, 2020 link) — I illustrate how the mirror-image of anterior ST elevation may simulate the depressed ST-T wave seen in lateral leads when there is LV “strain”. As a result — the anterior ST elevation and increased QRS amplitudes seen in ECG #1 are both features in the unifying diagnosis of LVH with LV “Strain”.



Final QUESTION: Did you notice in ECG #1 that the P wave in lead I is taller than the P wave in lead II?

  • WHY might this be so?



ANSWER to QUESTION #2: The reason the P wave in lead I of ECG #1 is taller than the P wave in lead II (and also the reason why the P wave and QRS complex in lead III in ECG #1 are both negative) — is that there is LA-LL Lead Reversal!

  • My favorite on-line “Quick GO-TO” reference for the most common types of lead misplacement comes from LITFL ( = Life-In-The-Fast-Lane). Simply put in, “LITFL Lead Reversal” into the Search bar of your internet browser — and the link comes up instantly!
  • In Figure-2 — I have put the initial ECG = ECG #1 on the TOP, with addition below it of a box listing the effects that LA-LL Lead Reversal has on the ECG.
  • In the BOTTOM of Figure-2 — I have inverted lead III — switched the position of leads I and II — switched position of leads aVL and aVF — and left aVR alone. I have labeled this new tracing as ECG #2 — and have placed this under the initial ECG — so that we can compare how correcting for the effects of LA-LL Lead Reversal would result in an ECG that would look like ECG #2. Therefore — Although clinical management in this case would not have been changed (because our interpretation of this patient’s ECG would still have been marked LVH and not acute anterior OMI) — Comparison of ECGs #1 and #2 tells us how much limb lead appearance would have changed IF all limb leads had initially been correctly placed.
  • NOTE: For another example of LA-LL Lead Reversal — Please see our August 28, 2020 post.


Figure-2: Showing the effects of LA-LL Lead Reversal — then taking another look at ECG #1! (See text — and See LITFL Lead Reversal).



LEARNING Points from this Case:

  • Some types of lead misplacement are obvious. Others (such as the LA-LL lead reversal in today’s case) can be ever-so-easy to overlook. The “tipoff” to LA-LL reversal in ECG #1 — is that the P wave in lead I is clearly larger than the P wave in lead II (and that is unusual when there is sinus rhythm).
  • Additional “tipoffs” that something may be amiss — include the negative P wave and negative QRS complex in lead III that can be seen, but which are not overly common (especially when seen in association with a P wave in lead I that is taller than the P wave in lead II).
  • Finally — Remember that marked LVH with overly deep anterior lead S waves may be accompanied by a surprising amount of anterior ST elevation which is usually not indicative of anterior OMI, but rather a mirror-image of LV “strain” as seen in anterior leads.



ADDENDUM: Criteria I favor for the ECG diagnosis of LVH.


Figure-3: Criteria I favor for the ECG diagnosis of LVH (This figure excerpted from My Comment in the June 20, 2020 post of Dr. Smith’s ECG Blog). Note that a number of voltage criteria listed here are satisfied in ECG #1.


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NOTE: My sincere THANKS to Anderson Santos (from Brazil) for catching this subtle example of lead misplacement!

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4 comments:

  1. Dr Ken, Your surmise that there had been LA-LL Lead reversal in the original 2012 blog is due to larger P wave in Lead 1 and inverted complexes in Lead III. Fine, but look at QRS-T in Leads I, aVLafter lead correction. They look totally out of form for LVH with strain. That said, we need to lookfor alternate reasons for larger P in Lead I and inverted complex in Lead III. As per the quoted reference below, left axis deviation of P wave is often associated with LVH. Inverted QRS in Lead III does not bother us very much, it is quite natural when the QRS axis in LVH takes the left
    ward direction.
    The Automatically assessed P wave axis predicts cardiovascular events in patients with cardiovascular risk. (J-HOP) Study.
    T Kabuloya et al
    EP EUROPACE, Vol 22, issue supplement 1,June 2020

    ReplyDelete
    Replies
    1. @ Dr. Balaubramanian — THANK YOU for your interesting comment. Unfortunately — your reference is to an entire issue of Europace …. and I didn’t see the article you are referring to there when I tried to access this issue …. (I’ll add that since I’m no longer in academics, I no longer have access to PubMed — so if this is an article you would like me to look at — please send the actual article to the above Contact email address, and then I’ll be glad to review the study on which your claim is based — :)

      What I can comment on, after 30 years experience reading all ambulatory ECGs ordered by 35 providers (as well as numerous in-hospital ECGs during my Attending duties during this time period) — is that you don’t always see similar changes for LVH and strain in the lateral limb leads as you do in the chest leads. It is not uncommon in my experience to see LV “strain” ST-T wave changes in inferior leads when you have marked LVH (usually the frontal plane axis is a bit more vertical than seen in ECG #2 — but not always). And you often do not meet voltage criteria in both limb and chest leads (very often criteria for LVH are met in one of these, but not the other).

      I maintain that the overly large and rounded P in lead I in ECG #2 in the absence of a reasonably-sized P wave in lead II — and in the absence of no more than a trivial terminal negative P component in lead V1 is NOT an expected finding. As stated — I don’t have access to the reference you mention — but both sensitivity and specificity of P waves on ECG for LVH is known to be extremely poor. I’m hesitant to accept that the P wave appearance in the limb leads of ECG #1 is truly predictive of LVH in the absence of more than the single reference you cite. Again — I’ll be glad to review the actual study you refer, to if you send it to us at the above Contact email address.

      THANK YOU again for your comment! The “beauty” of electrocardiography is that more than a single opinion for an interpretation will often be found — and I’m HAPPY to respectfully agree to disagree with you on this one.

      P.S. Unfortunately — the only way to prove 100% whether you or I are correct would be to repeat the ECG on this patient after verifying lead placement — and that is no longer possible to do — so we are left with these interesting discussions! — :)

      Delete
  2. Is there any reason why the last complex in v4 has a t wave inversion and not any other lead?

    ReplyDelete
    Replies
    1. Note how the ST-T wave is markedly different for each of the 3 beats in lead V4. This is especially true of the 3rd complex (which as you note shows T inversion). This type of bizarre variation from one complex to the next (especially when unphysiologic, as is the uncharacteristically deep T inversion for this 3rd complex that then RISES until it joins the P wave) is undoubtedly due to some type of ARTIFACT that is ONLY affecting the lead V4 electrode (ie, loose contact of that electrode? — :)

      Delete

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