Benign Normal Variant – Not so “Benign”

— Vernon R. Stanley, MD, PhD

©2017.  All rights Reserved.

In the blog post below, we will discuss the finding of “ST-segment elevation” and a few of the differential diagnosis to keep in mind as this observation is made on the ECG.  Please understand these are only a handful of differential diagnosis as regards ST-segment elevation; however for the sake of brevity we will narrow the discussion to comparison of the following, namely:

  • Pericarditis
  • Benign Normal Variant
  • Acute Anterior STEMI

These three are common presentations which can mimic each other and which frequently present a dilemma to the provider.


Acute Pericarditis

Clinical characteristics of acute pericarditis:

  • Mid-pleuritic chest pain
  • Pain worsens with recumbency
  • Pain relieved by leaning forward
  • Pericardial friction may be present
  • Most are idiopathic or viral in origin

ECG Clues suggestive of Acute Pericarditis:

  • Diffuse ST-segment elevation concave up (except Leads avR,V1)
  • ST-segment depression Leads avR, V1
  • Diffuse PR-segment depression (except Leads avR, V1)
  • May exhibit PR-segment elevation Leads avR, V1
  • May mimic Acute STEMI or Benign Normal Variant (Early Repolarization)
  • Lack of reciprocal ST-segment changes
  • R-wave progression usually normal
  • Quotient   ST/T = mm of ST segment elevation / mm height of T-wave  > 0.25 mm in Lead V6

PERICARDITIS Example A

 

Same Patient’s ECG  1 Year Prior:  Example B

 


Early Repolarization Example…

Now Acute Anterolateral STEMI….


Benign Normal Variant (Early Repolarization)

During your daily practice of medicine, you are frequently faced with the following scenario:

You are presented with a cardiogram which demonstrates minor, subtle ST-segment elevations concave up.  After analyzing the tracing, you have narrowed your choices to:

  1.  Benign Normal Variant (Early Repolarization).
  2.  Early, suspected Acute STEMI.

The sobering ramifications of this decision-making are obvious.  On the surface this challenge might appear to be straightforward, but in the clinical world you will encounter tracings that challenge even the most expert eye.

General comments regarding Early Repolarization Pattern

  • Serial tracings will show essentially no changes evolving (unless an infarction is evolving also)
  • Early Repolarization patterns essentially never show “terminal QRS distortion” (further discussion in our next blog posting)

Let us now review two serial tracings of an Acute Anterolateral STEMI – tracing “A” and tracing “B” at 1.5 hours.

TRACING A:  The tracing below represents the initial presenting cardiogram of a 32 year old with ACS.

The tracing below is a serial tracing of the same patient at 1.5 hours later…

 

I want you to focus on two aspects of these tracings:

  1.  The low point (nadir) of the S-wave of Leads V1, V2, V3
  2. The terminal R-wave of Leads V4, V5, V6


FINDINGS SUGGESTIVE OF ACUTE ANTERIOR STEMI (as opposed to benign normal variant)

  • ST-segment elevation, concave down (tombstoning, plateauing; sometimes concave up) in Leads V1 to V4 (maximum Leads V2, V3)
  • ST-segment depression of reciprocity (especially in Leads II, III, avF, V5, V6)
  • Poor R-wave progression
  • Anterior Q-waves present
  • Late transition
  • Presence of Hyperacute Ts
  • Terminal QRS distortion

Please be aware that sometimes the ST-segment elevation is concave up (even in the setting of the acute STEMI).  In these cases it is especially important to carefully look at all the clues, especially the “terminal QRS distortion”.

To summarize….


Please tune in to our next blog post where we will discuss the phenomena of terminal QRS distortion and it’s role in analyzing the ST segment of the ECG.

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