A 40-something with chest pain. Is this inferior MI?

This was sent by a Saleh Hatem, an avid reader of the blog.The patient presented with chest pain:There is a narrow complex tachycardia.Is there inferior ST Elevation?Here was my interpretation:What appears to be ST Elevation in inferior leads is really a P-wave that is contiguous with the QRS. (The next bump over is a T-wave that looks like a P-wave!).Since the P-wave is not inverted, it is NOT retrograde, and therefore it is a native sinus beat.  This sinus beat does conduct, but there is severely prolonged PR interval (severe first degree AV block), with a PR interval of over 400 ms.So: Sinus tachycardia with severe first degree AV block.Here is what he wrote:Her serial trop was negative.  Later ECGs confirmed your interpretation, Dr. Smith.  Thanks.The reader later sent these same followup ECGs:The sinus rate has slowed and now the P-wave is hidden in the T-wave.The sinus rate has slowed even more and now the P-wave comes after the T-wave, with a PR interval of just under 400 ms.===================================MY Comment by KEN GRAUER, MD (3/1/2020):===================================This is an insightful case succinctly explained by Dr. Smith. For the purpose of academic discussion — I will expand on a number of important points.For clarity — I have reproduced and labeled the ECG in this case in Figure-1.Figure-1: The ECG sent to Dr. Smith by a reader. The patient presented with chest pain. Presumably, this is her initial ECG...
Source: Dr. Smith's ECG Blog - Category: Cardiology Authors: Source Type: blogs