STEMI vs. early repolarization

Early repolarization (ER) is a common finding that can produce widespread ST segment elevation that may mimic STEMI or pericarditis

Convex and horizontal ST segment morphology is seen in STEMI and not early repolarization
Both STEMI and ER can have concave ST segment elevation morphology
J (junction) point = is present in all ECGs and occurs at the junction of the QRS complex to the ST segment
- - The J point marks the end of the QRS complex and is often situated above the baseline, particularly in healthy young males
Terminal QRS distortion is defined as the absence of both an S wave and J wave in either lead V₂ or V₃
- - S wave = any deflection at the end of the R wave that dipped below the level of the PQ junction
  - J wave = any positive deflection (notching or slurring) above the level of the ST segment at the J point
    - - Distinct from the J point and classically seen in early repolarization and hypothermia
Terminal QRS distortion is highly specific to STEMI (left anterior descending artery occlusion)
Absence of terminal QRS distortion does not rule out STEMI or early repolarization
Early repolarization has consistent characteristics in lead V₂ and V₃that allow it to be distinguished from terminal QRS distortion.
When J waves are present in early repolarization, S waves are significantly diminished and often absent in the same lead
Conversely, the absence of J waves in early repolarization correlated with high S wave amplitudes within the same lead

KEY PEARLS:

When debating between STEMI vs. early repolarization, look for terminal QRS distortion
In order to diagnose benign early repolarization, you must have either an S-wave or J-wave in both V₂ and V₃
Absence of either an S-wave or J-wave in either V₂ or V₃ is called “terminal QRS distortion”
Terminal QRS distortion is highly specific to STEMI
- - If V₂ has neither an S-wave nor a J-wave, it cannot be early repolarization
  - If V₃ has neither an S-wave nor a J-wave, it cannot be early repolarization
Absence of terminal QRS distortion can be either STEMI or early repolarization
Other helpful features seen with early repolarization:
- - No reciprocal ST depression (aside from V₁ & aVR)
  - ST elevation should always be concave upwards
  - ST elevation in lead II should be greater than the degree of ST elevation in lead III (STE II > III)
  - Height of ST:T in V₆should be < 0.25
  - Serial ECGs should not show evolving changes

Learn more about early repolarization here!

Reference:

Lee DH, Walsh B, Smith SW. Terminal QRS distortion is present in anterior myocardial infarction but absent in early repolarization. Am J Emerg Med 2016;34(11):2182–5. PMID: 27658331

Page updated

Google Sites

Report abuse