Regarding the point of the OP. Hell yeah, I'm going to ride. Maybe there's a small added risk to my heart, but there's surely an even bigger risk of serious injury in a crash. Not that I'm reckless- I try to be careful in every way I can, but riding is way too important to me. I'd rather have a shorter life that I enjoy by doing plenty of riding than a very long life sitting on the couch. And I doubt that the latter would be a long life because my mental and physical health would surely deteriorate without riding.
Regarding
big john , yeah, I feel for you. Both because of the weird heart things and especially because you aren't easily getting the care that you should be getting.
I may have symptoms similar to yours, I dunno. Up until 10 years ago, I could rev my heart in intervals as far as it would go and it would be just fine. But starting in my early 50s, I find that when I get my HR up "too high" too quickly*, I have this terrible feeling of malaise and feel the need to urgently get the HR down. This coincide with an unfortunate change in my heart rate recovery. Previous to this, after getting up to Z6, my HR would go right down by 50-60 bpm in the following 60 seconds. Ever since, it doesn't. It doesn't go own at all for the first 10-15 seconds after an interval ends, and after 60 seconds, it's gone down by 20-35 bpm.
I've had pretty much every kind of test, carried that 24 hour monitor that records everything, etc. Never been able to reproduce it in a way that the doctors could detect. An no doctor (I've seen multiple cardiologists, pulmonologists, etc.-_ I do have good insurance) has heard this description and identified a recognizable medical problem. And never had any evidence of afib. But it comes back - particular doing intervals - and I just hate it.
But I haven't stopped pushing myself or going full gas when I'm able, and nothing really bad has happened. Except that obviously, it limits my athletic ability during hard efforts. So maybe it's harmless. Or maybe one day I'll drop dead on the bike.
*"Too quickly" I can get the malaise by doing 60 second intervals (60 seconds on/60 seconds off) at 140-150% of FTP, and the feeling may show up at 170 or 175 bpm, say after the 4th or 5th interval. But if I'm putting in a hard steady effort at 120% FTP, I can go for 5 minutes and my HR will go up to 178 or 180 bpm, without the malaise.