A middle aged male had chest pain.  There was suspicion of acute MI.

The initial ECG was texted to me:

The QTc is 423 ms.  There is a large amount of ST elevation and Massive T-waves in V2 and V3, worrisome for LAD occlusion.  However, there is also excellent R-wave progression.

A repeat ECG was done a short time later:

No definite change.  Computerized QTc is 399 ms.

The potassium was 4.5 mEq/L.

Both of these ECGs are very worrisome for STEMI, but not diagnostic even though the second one meets criteria for STEMI (greater than 2 mm at the J-point in 2 consecutive leads).  Early repolarization can look like this, however.

So the formula for differentiating acute LAD occlusion from Early repolarization was applied:

See sidebar for calculator:

The exclusions are CRITICAL (in red)

Applying the formula to ECG 1, we get 22.025.  This is about 97% sensitive for LAD occlusion at a cutoff of 22.0, and 92% sensitive at a cutoff of 23.4.

If we apply to ECG 2 (which has MORE ST elevation), we get 19.63 (very low).

This ECG is so worrisome that I would not be entirely convinced that this is not MI.  But I would not activate the cath lab without more information if it is a strain on resources (nighttime, weekends, for instance).

A formal echocardiogram with contrast was done and showed no anterior or apical wall motion abnormality.

The patient ruled out for MI.

Learning Points:

1. When the differential is LAD occlusion vs. Benign Early Repol, the formula may help you to rule out STEMI

2.  If it is STEMI, there will be a Regional Wall Motion abnormality.  If the equation indicates Early repol and you don’t want to overuse scarce resources, then obtain an emergency high quality ultrasound to look for a wall motion abnormality.