I take metropolol for an irregular heartbeat due to aortic stenosis, a valve efficiency problem. I used to go up to 165 bpm or so, then it would stay up there even after I backed off. I had a dizzy spell while riding a flat road, just cruising along, at 165 bpm. I am an ex racer, who has been riding seriously for 20 years after several years off the bike. When I had it checked out, aortic stenosis was the diagnosis. With the metropolol, it's like a speed governor on an old U-haul truck. It usually holds me at around 140bpm max, comes back down quickly when I back off. I've lost around 40 lbs. and continue to do 40-50 mile rides at a 15-17 mph average, and generally feel pretty good, if a little slower. When it first happened, and, before the medication, I was afraid my serious cycling days were over, and started feeling apprehensive about even going out. That was three years ago. Now I go in for an ultrasound once a year (next one is tomorrow), and then I ride on from there, fingers crossed. My usual ride has a avg bpm around 100-110, with a max of 130-140. I'm usually in the mid 40s at rest.
One more thing. I never had any symptoms, until 2016, when I fell twice on Eroica (damn toe clips) and banged up my knee. I backed off on riding till my knee was better, then shortly after restarting, I started getting the wierd heart issues. I thought it was just due to time off the bike, which is why it took me so long to get it looked at. On my ride log, I had about 13 heart rate issues over 75 rides, before the above mentioned dizzy spell.
Good luck with yours.
Last edited by Slightspeed; 07-17-19 at 07:36 PM.