Early repolarization or LAD occlusion?

41 year old male complaining of chest discomfort.

  • Past medical history: Asthma
  • Medications: Inhaler (unknown type)

EMS finds the patient sitting in a chair.

The patient appears acutely ill. His skin is cool, pale, and diaphoretic. Breath sounds clear bilaterally.

  • Onset: At rest
  • Provoke: Nothing makes the pain better or worse
  • Quality: “Heavy” and “unrelenting”
  • Radiate: The pain does not radiate
  • Severity: 8/10
  • Time: The patient has had similar episodes that cleared up after using his inhaler

Vital signs are assessed.

  • RR: 20
  • HR: 60
  • BP: 112/84
  • SpO2: 91 on RA

The cardiac monitor is attached.


A 12 lead ECG is captured.


What’s going on here?

This following ECG was captured en route to the hospital.


Look very carefully at lead V3!

The S-wave has been lifted up above the isoelectric line!

This is sometimes referred to as “terminal QRS distortion” and it helps differentiate LAD occlusion from early repolarization when it occurs in lead V3.

(See also: Terminal QRS Distortion Due to LAD Occlusion at Dr. Smith’s ECG Blog.)

In this case it’s a change on serially performed ECGs which makes the finding even stronger.

It’s also worth noting that the initial ECG shows upwardly convex ST-segment elevation in lead aVL with terminal T-wave inversion. There is also a subtle reciprocal change in lead III.

This case was difficult because our normal “tricks” to differentiate between acute anterior STEMI and benign early repolarization lead don’t work. R-wave progression is intact and the QTc is not prolonged.

Updated 04/23/2016


4 Trackbacks

Leave a Reply

Your email address will not be published. Required fields are marked *