Difficulties with "Acute myocardial infarction in last six months"

Sorry for that. We will fix the mapping on the nearest ICD10CM re-run.
As for now, adding the source_concept_id of I21.A1 to the narrow cohort would be the only choice.

As for me, they are different. The only thing “History of condition” construct means is that the debut of the condition (or one of its episodes) has happened in the past (a day or 10 years ago). While old infarction implies the combination of clinical/laboratory signs of “healed” myocardial infarction. We introduced the new enhanced history of concepts, but even then the duration needed for infarction to become old is always different.

So, I’d exclude this concept and others similar.

For sure, you can pick those with Acute. For the rest, SNOMED isn’t 100% clear since some of the concepts aren’t fully defined by their attributes.
I’d recommend going through the descendants and sorting them out by their clinical definition.