Stable or not, it won't matter. For Family Class sponsorships, there is no demand problem. Really they are looking for: TB (chest x-ray), HIV (which they still permit, but I think there is a special clause), Syphilis (which the doc finds via blood test, and starts treating immediately), etc. Stroke, heart, etc; no issue.
I am glad to hear he is recovering! My dad had a stroke as a result of a special syndrome (who's name escapes me). The clot is lodged within his brainstem. My mom is an RPN with decades of time working with stroke victims. She was on him immediately to start relearning. So, present day, the risk of stroke or issue from the previous event is near zero. He has regained everything. Mentally, he gets overwhelmed by crowds and traffic. Otherwise, nothing lasting.
So, really, don't worry at all. You're still on the right timeline, and the medical won't be a big deal. Promise