Thanks @Mansour Khaddr for your thorough explanation. As you indicated AF was likely the likely for his symptoms. There was some concerns about the slight ST elevation in aVL and I (not V2) to be related to stent thrombosis, and given his CP he was taken back to the cath lab and stent was patent.

In his case, the CP was pleuritic and in combination with AF it was felt this is just a post-MI pericarditis. The EKG changes were related to his recent MI, but with tachycardia the residual STE got exaggerated.

He was treated with NSAID and Colchicine and did very well.

I was surprised to see pericarditis in such a small and focal MI with very minimal elevation of troponin and early intervention.

Thank you all for your enlightening discussion.