Here is the ECG of a man with 2 hours of chest pain.  He had a history of MI with LAD stent.  I cannot find his prehospital ECG, but the medics did not activate the cath lab.

Diagnosis?  See Below.

Inferior STEMI with hyperacute T-waves, trace ST elevation in inferior leads with reciprocal ST depression in aVL and reciprocal T-wave inversion in aVL.  The T-waves are massive in comparison to the QRS.  There is T-wave inversion in V2 that is highly suggestive of posterior MI as well.

This is diagnostic of inferior MI.  Nothing else does this.

The clinicians were uncertain, but they suspected MI. They did a right sided ECG which was not helpful.

They did another right sided ECG 32 minutes later.

In spite of absence of evolution on serial ECG, the cath lab was activated.

There was a 100% occlusion of the distal RCA.