Pacemaker (Bradycardia) and a-fib, beta blocker, Xarelto, aged 78. My heart rate sometimes goes bonkers, but I don't feel any symptoms. My doc has told me repeatedly that I can drive my HR as high as I can. Usually that means 115 if I'm lucky and fierce.
A couple of weeks ago, I did a 4 mile loop at 160-170, but the next 2 loops were at 105. I spend some time on each ride going faster than whatever my 'normal' may be for that day.
I'd like to ride in zone 3 and 4 a lot, but with the beta blocker, I have no idea what the zones are.