Saturday, March 27, 2021

ECG Blog #208 (ECG MP-25) — ST Elevation but No History


The computer interpretation of the ECG shown in Figure-1 said the following — “Sinus rhythm; Normal ECG.”  

  • Do you agree with the computer interpretation?
  • In the absence of any history ... — WHAT are your diagnostic considerations?
  • WHICH of these considerations is most likely?

 

Figure-1: How would you interpret this ECG? (See text).


 


 

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NOTE #1: Some readers may prefer at this point to listen to the 9:50 minute ECG Audio PEARL beforereading 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-25).

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 Today’s ECG Media PEARL #25 (9:50 minutes Audio) — Pearls & Pitfalls regarding the ECG diagnosis of Acute Pericarditis.

 

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NOTE #2: I have excerpted a written summary on “My Take” for ECG diagnosis of Acute Pericarditis from my ECG-2014-ePub. This appears below in the Addendum (in Figure-3 through Figure-7).

  • CLICK HERE — to download a PDF of this 9-page file on Pericarditis.

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MY Approach to this Tracing:

As always — I favor a Systematic Approach for every ECG I encounter (This Systematic Approach reviewed in ECG Blog 205). My descriptive analysis of the ECG shown in Figure-1 is as follows:

  • The rhythm is regular at ~80/minute. Upright P waves with a constant PR interval are seen in lead II — so the rhythm is sinus. Intervals (PR, QRS, QTc) and the axis (which is about +70 degrees) are normal. There is no chamber enlargement.

 

Regarding Q-R-S-T Changes:

  • There are small and narrow Q waves in the inferior and lateral chest leads.
  • R wave progression is remarkable for the presence of a taller-than-expected R wave in lead V1 — with early transition occurring between lead V1-to-V2. Normally, there is no more than a very small r wave in right-sided lead V1 — and transition (where the R wave becomes taller than the S wave is deep) does not occur until at least lead V2-to-V3.

 

Assessment of ST-T waves:

  • There is subtle-but-real ST elevation in multiple leads (horizontal dotted RED lines in Figure-2). There is an upward concavity (ie, “smiley”-configuration) to the elevated ST segments — with suggestion of J-point notching in several of them (best seen in leads V2 and V6).
  • Assessment of ST elevation in Figure-2 is made more difficult by the presence of subtle-but-real PR depression in a number of leads (best seen in the inferior leads, and in leads V4 and V5). There is also slight PR elevation in lead aVR.
  • There is T wave inversion in lead aVL (within the dotted BLUE oval in Figure-2).


Figure-2: Horizontal dotted RED lines show subtle-but-real ST elevation in multiple leads. The T wave in lead aVL is inverted (See text).



PEARL #1: The term PR depression will often come up when a diagnosis of acute Pericarditis is contemplated. 

  • PR depression is said to be present when the horizontal PR segment is depressed below the ST segment baseline (as determined here with respect to the T-P baseline).
  • Support that the finding of PR depression is real may be derived by the finding of PR elevation in lead aVR. 
  • Unfortunately — there are problems with use of PR depression as a diagnostic criterion for acute Pericarditis. These include: i) False positives (because other conditions, including acute MI and normal repolarization variants may also at times manifest PR depression)iiFalse negatives (because PR depression is not always seen with acute pericarditis)andiii) Inter- and intra-observer variability in detecting PR depression (therefore limited reliability in my experience for the validity of this finding)
  • BOTTOM Line: It is probably best not to base your diagnosis of acute Pericarditis on whether or not you see PR depression.

 

PEARL #2: While important to note the presence of symmetric T wave inversion in lead aVL of Figure-2 — this is not necessarily an abnormal finding!

  • Considering the small amplitude of the QRS complex in lead aVL — the size of the inverted T wave in this lead is relatively large. That said — T wave inversion may sometimes normally be seen in lead aVL — especially when there is a relatively vertical frontal plane axis and the QRS is predominantly negative in lead aVL (as we see in Figure-2). This is because the normal T wave axis often follows fairly close behind the QRS axis in frontal plane leads (ie, isolated T wave inversion may be normal if seen in lead III, lead aVF or lead aVL when the QRS complex is predominantly negative in the lead with T wave inversion — See ECG Blog #79).
  • BOTTOM Line: The T wave inversion that we see in lead aVL of Figure-2 may or may not reflect an abnormal finding.

 

PEARL #3: The larger-than-expected R wave in lead V1, with early transition (mentioned above under R-wave progression) is of unknown significance. The purpose of including an R in my memory aid for assessing Q-R-S-T Changes — is specifically so that the finding of early transition is not overlooked.

  • BOTTOM Line: The list of clinical entities to consider whenever you encounter a taller-than-expected R wave in lead V1 were reviewed in ECG Blog #81. Among these entities is posterior infarction that occurred at some point in time. This could be relevant to today’s case — given questions regarding inferior lead ST elevation and possible reciprocal ST-T wave change in lead aVL. 

 

Putting It All Together:

Some history is needed in order to know what (if anything) to do with the ECG shown in Figure-1! This ECG was one of many in a “pile” of tracings that I was given to read in our ambulatory care clinic (during the time I was charged with “official interpretation” of ECGs for our 35 medical providers). There was no indication on the ECG of any history.

  • The 1st thing I did was to cross out the computer interpretation of this ECG, which said: “Sinus rhythm; Normal ECG.”  Although subtle — there is no denying the above Descriptive Analysis findings of: i) Some ST elevation in multiple leads; ii) T wave inversion in lead aVL that could potentially reflect reciprocal changes; andiii) Early transition with a taller-than-expected R wave in lead V1.
  • I could not rule out the possibility of infero-postero MI at some point in time.
  • I also could not rule out the possibility of potentially recent pericarditis — given at least slight ST elevation in more leads than is generally seen with repolarization variants.
  • That said, my “sense” (intuitive feeling) — was that the above-described ECG findings in today’s case were probably not acute.
  • FOLLOW-UP: It was clear that I needed to find out the history on this patient. It turned out that the patient was an elderly, non-English speaking woman. Through translators, we learned she had no cardiac symptoms in recent months. Physical examination at the time this ECG was obtained was unremarkable. The reason for obtaining the ECG appeared to be as part of a general assessment in a new patient. Whether this woman had a previous cardiac event was uncertain — as there were no medical records. Taking this history into account — I concluded there was nothing acute on her ECG, and no need for further investigation at this time given her elderly age and lack of cardiac symptoms.

 

PEARL #4: Each ECG tells a story. Without the clinical history — that story is incomplete. I find it humbling (and clinically essential) to appreciate — that identical findings on an ECG may lead to vastly different clinical interpretation depending on what is going on with the patient at the time the ECG was taken.

  • Had the history in today’s case been that of a young adult with recent viral illness and pleuritic chest pain — this ECG could have been consistent with recent (or acute) pericarditis.
  • Had the history been that of a middle-aged or older adult with chest pain that began over the previous day — one would not be able to rule out the possibility of recent (or acute) infero-postero MI on the basis of this single tracing.
  • Therefore — clinical correlation is an essential part of our interpretation.
  • That said, by definition — a computer interpretation is made without benefit of clinical history.

 

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ADDENDUM (3/27/2021): In the following 5 Figures — I post written summary from my ECG-2014-ePub on the ECG diagnosis of Acute Pericarditis.

  • CLICK HERE — for a PDF of this 9-page file on Pericarditis that appears in Figures-3-thru-7.



Figure-3: How to make the diagnosis of acute Pericarditis (ie, use of the History and Physical Exam).



Figure-4: ECG findings (4 Stages of acute pericarditis — with attention on diagnostic Stage I). How helpful is PR depression?


 

Figure-5: PR depression (Continued). Spodick’s sign. Acute MI vs Pericarditis vs Repolarization variants?


 

Figure-6: Acute MI vs Pericarditis. ECG findings with acute Myocarditis. Pericarditis vs Early Repolarization?


 

Figure-7: Pericarditis vs Early Repolarization? (Continued).


 

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Relevant ECG Blog Posts to Today’s Case: 

  • ECG Blog #205 — Reviews my Systematic Approach to 12-lead ECG Interpretation (outlined in Figures-2 and -3, and the subject of Audio Pearl MP-23-LINK in Blog #205).
  • ECG Blog #79 — Reviews which leads may normally manifest Q waves and/or T wave inversion.
  • ECG Blog #81 — Reviews the Common Causes of a Tall R Wave in Lead V1.
  • ECG Blog #207 — The ECG Computer Report: Friend or Foe?





5 comments:

  1. “Each ECG tells a story. Without the clinical history — that story is incomplete.”
    Perfect, Professor Ken Grauer. I teach ECG here in Brazil, I highly value this correlation with clinical data. Thanks for sharing interesting cases.

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    1. Obrigado Nestor pelas boas palavras. Estou feliz que o meu Blog chegou ao Brasil — :)

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  2. Dr Ken thank you for this excellent post of asymptomatic ST elevation in infero-lateral leads. There is concave , mild (1 to 2 mm ) ST elevation with unmistakable J waves in II, III, aVF,v2, v4,v5 and V6 clinching the diagnosis of normal variant ST elevation/ Benign Early Repolarisation.
    with regards, Dr.R.Balasubramanian. PONDICHERRY-INDIA

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  3. Dr Ken, I forgot to add an important point and that is why this addendum. Infero-lateral J waves are not benign, they could land
    the patient in malignant ventricular arrhythmias. with regards,
    Dr.R.Balasubramanian.

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    1. @ Dr. R.Balaubramanian — THANK YOU for your comments! Clearly IF the patient was a young adult without worrisome symptoms — then I would agree with you. But in the absence of any history — I maintain that it simply is not possible to be 100% certain that the ECG in Figure-1 is benign. Early repol usually doesn’t produce ST elevation in 8-9 leads … — and even though narrow, there ARE small Q waves in each of the inferior leads — the shape and size of the ST segment and T wave in lead aVL is not necessarily benign — and R wave amplitude in both leads V1 and V2 IS taller-than-expected. And, what’s to say that this might not be a patient with a “baseline” of early repolarization + early acute changes … The Bottom Line for me remains the same as I suggest in Pearl #4 = “Without the clinical history, the story told by this single ECG is incomplete”. THANKS again for your interest and comments! — :)

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