Benign Early Repolarization vs. Anterior STEMI

Benign Early Repolarization

• Benign Early Repolarization is the most common, “normal”  ECG variant
• Occurs in about 1% of the population 
• Degree of J point elevation is usually highest in the mid-left precordial leads (V2-V5) and never seen in aVR
• Isolated benign early repolarization in limb leads is very rare (inferior II, III, aVF and lateral I, aVL
• BER may be confused with STEMI criteria or those with STE 0.1-1.0 mm that may not meet STEMI criteria but may still be concerning for early anterior MI (can mimic BER findings) 

ECG Findings that are more typical of BER: 

1. STE at the J point with upward concavity 

• Convex STE morphology is highly specific for AMI
• LAD occlusions can be seen with concave morphology 
• In general, do not use this alone to differentiate BER vs. AMI

2. Notching at the J point

Courtesy of lifeinthefastlane.com

3. Diffuse STE often greatest in V3-V4. Use the ST/T wave ratio to differentiate BER from pericarditis. (ST = height of ST-segment as measured from J point; T  = T wave amplitude in V6) 

• ST/T  < 0.25 = BER 
• ST/T > 0.25 = Pericarditis 

4. STE or J point elevation in BER can have concordant prominent T waves with large amplitudes 

5. Normal R wave progression in BER 

• R waves should increase in size through the precordial leads until only a small S remains in V6
• There should never be poor R wave progression in BER

Good R wave progression in BER

Poor R wave progression in old anterior MI

6. Relative Stability from one ECG to the next: visualization of BER can vary with heart rate (sometimes minimizes in tachycardia) and can sometimes normalize with age 

ECG findings more suggestive of anterior STEMI:

• Reciprocal Changes in opposite leads (II, III, aVF for anterior MI)
• Pathologic Q waves in anterior leads (Q waves in leads V2-V3 ≥ 20 ms; can develop < 1 hour after acute MI)
• J point emergence at 50% or greater of the R wave height in leads with a QR
• S wave disappears (does not extend below the baseline) in leads with an RS wave
• Terminal QRS distortion (particularly in V2-V3)

Dr. Smith’s Formula 

• Retrospective review of patients with subtle anterior MI vs. BER
• Created a formula using logistic regression to predict AMI vs. BER: 86% Sensitive, 91% specific
• Exclusion Criteria: > 5 mm STE, non-concave STE, inferior reciprocal changes, anterior ST depression, terminal QRS distortion in V2-V3
• Does not apply in LVH

  Life in the Fastlane – Benign Early Repolarization

• Concave up STE V2-V6, II, III, aVF
• J point notching II, III, aVF
• Prominent, concordant T waves

Post by Dr. Delna John, PGY-4

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Charles Murchison

Latest posts by Charles Murchison (see all)

• Benign Early Repolarization vs. Anterior STEMI - February 20, 2020
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