I was shown this ECG and asked if I think it is a STEMI.  What do you think?

Answer Below

I answered that it does not meet any criteria for STEMI, but that there are hyperacute reciprocal (negative) T-waves in I and aVL and this cannot be anything other than inferior STEMI, especially since the ST depression in V2-V5 suggests concomitant posterior STEMI.

The ECG findings resolved before cath.  At cath, there was an 80% hazy thrombotic lesion in the RCA.  Thus, this was indeed an acute RCA occlusion.  Echo the next day showed an inferior wall motion abnormality.

Lesson: Reciprocal ST-T changes are often more pronounced than the ST-T changes overlying the affected myocardium.  This is particularly common when there is lateral STEMI with inferior ST depression (see these two cases).

Here is a case in which there are both inferior and reciprocal hyperacute T-waves.