Didn’t comment for a start with this as the scenario was a bit close to home for me re possible reason for demise.
However, if it only prevents one of us following the same path, a few things I can recommend.
Once we go into the 30-40 bracket, the body stops producing a lot of good bits that keeps us healthy. (obviously back when we chased dinosaurs, when we reach this point, the young guns took over and we sat back and just bludged and feasted on their kills)

1 Get cloistral check, if its good, your doing well, if its borderline, then plenty of medication to get it back on track.
2 Have your medico set up a stress test, not definitive, but its better than coming unstuck. Its like a over temp warning on your car, it gives you a warning. You have to make the fix.
Some may not want to go down this road, but for goodness sakes, just do it for those around you. Its not cool to suffer and go this way.
If your over 40 its strongly recomended, if your over 50 its a "must"
Condolences to his family and friends.
Mineral