That's what what happened to me...1st dose of Toprol; even at 12.5mg I ended up in the ER with such a low hr/bp...
I had an ablation; given Zebeta and no pvc's for about 3 months; then they returned full force, and I tried something else but my bp/hr stayed really low and I felt miserable - tired all the time, my dizziness & fainting increased and dr's didn't know why.
I told them no more meds, until a new dr suggested Inderal which helped tremendously, it's just a shorter term duration.
Ask about changing to another beta blocker. Atenolol and Toprol did nothing but slow my heart rate down some, actually seemed to increase PVCs. Switched to bystolic, a newer medication, and it helped. Still have them but they seem better most of the time.
Unfortunately because my blood pressure is normally low, they don't want to give me a high dose of Toprol. I am only on 25mg 1x a day. Both docs said that they would not go above 37.5 mg.
You are doing what you can, that is, trying to find out what works for you. It is obviously something you are doing/not doing that caused them to go away. I never celebrate when mine disappear. Perhaps you need a slight bump-up with the Toprol? I found that 75mg of Toprol-XL 2x/day works better than 100/am and 50pm or 150mg am. Go figure. Good luck