My son is young with a lot of PVCs and fast HR they didn't want him on the beta either.
low dose beta blocker should be safe to take!
How fast is the beat? What did the doctor say? What is your BP? Did your doctor do further tests to determine if your heart is structurally normal? Did you have a Holter monitor or event recorder?
If so, did the doctor say exercise was okay? This can relieve stress, help lower BP and regulate heartbeat IF it is approved by doctor.