I'm pretty sure he got checkups often, he was a cancer survivor and I swear he mentioned black people needing to do checkups. For what could have happened (speculation), besides any chest pains, which should have prompted a visit to the ER, that isn't something that will show up in a basic checkup, you can go to a cardiologist for things like that. Expensive stuff in America, even more so for black people, so that needs to be handled both socially and politically.
Regarding a possible nurse being present, yes, the very basic thing you do in that situation, after contacting emergency services, or at best getting someone else to do it, is immediately check for responsiveness/breathing and then you begin CPR. It should be noted, the effectiveness of even a nurse administering CPR in response to a cardiac arrest is going to slim to nothing, your chances of survival if it happens in a hospital is still slim to none, and if you do survive it either isn't for long or you will wish you didn't survive as a decent chunk of survivors die months or a year or so afterwards due to the impact cardiac arrest can have on the body. So there's isn't much the supposed nurse could have done outside of CPR, which I would assume she would administer after the shock of it all, it would be too late though.