It's one of those questions with no absolute right or wrong answer, for too many reasons for me to mention.

If you're not sure if it's a wise decision, maybe don't rush into anything just yet. Because once you've said it, it's out there and you won't be able to retract what you've said.

On the other hand, you have known them for 4 years and have somewhat discussed MI before.

If you choose not to tell them; I don't personally see it as perpetuating the stigma; but I do see your point.

There are a number of personal reasons I don't disclose my MI to others.