I don’t see infarct as much as inverted p waves indicating a junction rhythm
Junctional rhythm can be diagnosed by looking at an ECG: it usually presents without a P wave or with an inverted P wave. Retrograde P waves refers to the depolarization from the AV node back towards the SA node.
ectopic atrial rhythm not originating from the sinus node.
Note: Altered P wave morphology is seen in left or right atrial enlargement.