@plumto66 I've been on metoprolol for roughly 2.5 years. For me, also, it has some adverse side effects. I'm on it because I was sitting peacefully in my PCP's office for a wellness checkup in JAN 2024 and the EKG showed my HR was at 117 and I was in atrial flutter (but I felt just fine). My typical resting HR was closer to 48-52 at that time. Was much lower (high 30's to around 42) when I was much younger; am 75 now and was very athletic my entire life (since around 8 years old); baseball for 12 years, regular racing on my bicycle for timed trials 10-12 years old, miler, x-country varsity, ice hockey, soccer, more bicycle training and some racing, road running and racing including marathons (high weekly mileage volumes starting at 28 years old), regular HIIT added to endurance exercise for ten years prior to the ambulance trip to the hospital from my PCP's office in JAN 2024 and sustained, pretty intense endurance exercise for decades . You may know metoprolol is a beta-blocker. Like you, it suppresses my HR. And when trying to elevate it during exercise, the experience is very unnatural. I used to do 80-95% of max HR during HIIT, but my cardiologist says don't go above 75% because, sporadically, as I push the effort higher to try to get. to even 70% max HR, it will surge to 125, 140 or possibly higher. When I stop, it comes down to around 75 bpm pretty rapidly; my paced HR is 70. So, you might have a conversation with a/your cardiologist to see if switching to a calcium channel blocker such as diltiazem would be better for you; it may be no better. Others might suggest, if possible, to consider an ablation to try to remove the arrhythmia with the goal of getting off anti-arrhythmic drugs like metoprolol (or diltiazem). Or try electro-cardioversion before trying an ablation.