ECG Blog #329 — Normal Variant in a Young Adult?

 

The ECG in Figure-1 — was obtained from an asymptomatic young adult as part of his pre-employment medical exam. The patient has been healthy, without medical complaints. On seeing this ECG — an Echo was obtained, which was reported as a normal study.

• How would YOU interpret the ECG in Figure-1?
• Is this a "normal variant"?

Figure-1: The initial ECG in today's case. (To improve visualization — I've digitized the original ECG using PMcardio).

MY Thoughts on the ECG in Figure-1:

This case was sent to me via the internet. I interpreted the ECG as follows:

• The rhythm is sinus at ~80-85/minute. The PR and QRS intervals are normal. The QTc is at most borderline prolonged. The frontal plane axis is normal (ie, about +20 degrees).
• There is no chamber enlargement (ie, Given that the patient is a young adult, and presumably less than 35 years old — QRS amplitude is not increased).

Regarding Q-R-S-T Changes:

• Q waves — At most, there are tiny q waves in the high lateral leads (I,aVL) — which are "normal septal q waves".
• R Wave Progression — There is early transition (with R=S already by lead V2).
• ST-T Wave Changes — There is ST elevation in leads V1-V3 (attaining ~1.5 mm in lead V2) — with steep descent of the T wave in lead V2, that leads into terminal negativity of the T wave. But the most remarkable ECG finding — is the symmetric T wave inversion seen in multiple leads (which is surprisingly deep in leads V3-V5).

IMPRESSION: Although this young adult was asymptomatic at the time this ECG was recorded — the ST-T wave changes seen in Figure-1 are not consistent with a simple "normal variant" pattern.

• There are many types of early repolarization and repolarization variant patterns (See My Comment at the bottom of the page in the May 23, 2022 post in Dr. Smith's ECG Blog).
• Included among the more common of these variant patterns is anterior TWI (T Wave Inversion) — either as a "persistent juvenile T wave pattern" — or — in association with a repolarization pattern characterized by coved ST elevation with terminal TWI. The problem is the difficulty that may sometimes arise when trying to distinguish between benign vs pathological patterns (especially between HCM [Hypertrophic CardioMyopathy] — and ACM [Arrhythmogenic CardioMyopathy]).
• Although previously referred to as ARVC (Arrhythmogenic Right Ventricular Cardiomyopathy) — variants that also involve the LV (Left Ventricle) or both ventricles have been increasingly described. The overall incidence of ACM is ~1/5,000 — with anterior TWI being a primary diagnostic criterion when there is predominant RV involvement — and lateral TWI when there is predominant LV involvement (Corrado et al — Circulation Research 121:784-802, 2017).
• Among the ECG criteria associated with HCM — anterior TWI may be seen in ~3% of cases (Other ECG criteria associated with HCM are described in ECG Blog #81). If there is doubt when considering the possibility of HCM — Echo is diagnostic.

Overall — the ECG may provide clues to whether a certain pattern of ST-T wave changes is likely to be benign or pathologic. That said — ECG screening is not a perfect tool. Although detailed discussion of this subject extends beyond the scope of this ECG Blog — I list below some generalities that may be helpful in assessment (D'Ascenzi et al — Clin Cardiol 43(8): 827-833, 2020) (Walsh, Smith et al — J Electrocardiog 56: 15-23, 2019) (Wilson et al — Br J Sports Med 46(Suppl-1), 2012).

• Clearly, in a patient with any suspicious ECG findings — the presence of any symptoms (ie, syncope-presyncope; concerning arrhythmias; chest pain) — and/or — a positive family history (ie, for sudden death at any early age — or malignant arrhythmias) — immediately places that patient in a higher-risk category (for which more complete evaluation is indicated).
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• Anterior TWI when seen in asymptomatic subjects, is more likely to be benign (especially in black athletic individuals) when there is: i) J-point ST elevation; ii) J-point notching or slurring consistent with early repolarization; iii) Biphasic TWI; iv) When anterior TWI does not extend beyond lead V3 (although healthy black athletes occasionally manifest anterior TWI up to lead V4); and/or, v) When there are voltage criteria for LVH.
• Anterior TWI is more likely to be associated with ACM (or other underlying structural cause) IF there is: i) Anterior TWI that is preceded by either an isoelectric or depressed ST segment; ii) Low voltage on ECG; iii) Q or QS waves; and/or, iv) PVCs.
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• Overall — the finding of Lateral TWI (with or without inferior TWI) — should increase suspicion for an underlying cardiomyopathy. To emphasize — that lateral TWI may be a benign finding. But there should be a very low threshold for additional evaluation when lateral TWI is seen in an asymptomatic subject.

What About Today's Case?

As noted above — the ECG in today's case is clearly abnormal. Although this younger adult is completely asymptomatic — the pattern of deep, diffuse T wave inversion (in no less than 8 leads — and including inferior and lateral lead distribution) — is beyond that expected as a benign normal variant pattern.

• It is good that an Echo was already ordered on today's patient. Although initial interpretation of this Echo was normal — further review of the Echo study raised the question (without definitive answer) of some apical abnormality.
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• NOTE #1: An underlying cardiomyopathy is not necessarily ruled out by a normal Echo. When suspicion of underlying pathology is higher — cardiac MRI (Magnetic Resonance Imaging) is definitely indicated, with special techniques including contrast enhancement to optimize detection of ACM and apical HCM (See Corrado et al — Eur Heart J 41(14):1414-1429, 2020 — for more on MRI evaluation of ACM). 
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• Results of cardiac MRI are pending in today's case.
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• NOTE #2: In a certain percentage of cases — abnormal TWI on ECG may predate anatomic evidence of an underlying cardiomyopathy by as much as a number of years. As a result — serial evaluations over time may be indicated in selected higher-risk patients (and/or those with especially abnormal ECG findings).
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• Additional components of full evaluation include a careful family history — and at times, exercise testing and 24-hour Holter monitoring. 
• Use of genetic testing (with consideration of a familial channelopathy) extends beyond the scope of this blog post.
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• P.S.: Although the ECG appearance of the ST-T wave in lead V2 resembles that of a "Wellens'-like T wave" — today's case is not consistent with Wellens' Syndrome! This is because a specific history (ie, of prior chest pain that has completely resolved at the time the ECG is recorded) — is essential for the diagnosis of Wellens' Syndrome. Instead — today's case is from an asymptomatic young adult who is in for his pre-employment exam. It's important to remember that other clinical entities (ie, completed infarction, LV aneurysm, LVH, repolarization variants, etc.) may manifest similar ST-T wave changes that are seen with true Wellens' Syndrome. (See ECG Blog #320 — for more on what Wellens' Syndrome is and is not).

Some Examples of Repolarization Patterns:

• ECG Blog #60 — for an example coved ST segments with diffuse TWI as part of a pre-participation physical performed on a healthy 20-year old football player.
• ECG Blog #254 — for an example of coved anterior ST Elevation with terminal T wave negativity resembling "Wellens-like" ST-T waves.
• My Comment at the bottom of the page in the September 15, 2020 post of Dr. Smith's ECG Blog (for a middle-aged adult with ST elevation and peaked T waves that turned out to be a repolarization variant).

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Acknowledgment: My appreciation to Mohamed Wafiq Shoukry (from Kuwait) for the case and this tracing. 

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Related ECG Blog Posts to Today’s Case:

• ECG Blog #205 — Reviews my Systematic Approach to 12-lead ECG Interpretation.