I had a couple of episodes of SVT 3 years ago and was put on 25 mg of atenolol. I did great up until my husband had a heart attack. The day after I found out he had to have a quadruple bypass I went into what I now think was a fib. It went back to normal after about 4 hours. Next day I was in bigeminey for hours. I blamed it on stress. A couple of months later my heart started going crazy with tachycardia, PVCs and PACS (seen in ER twice). They increased atenolol to 50 mg. Still had loads of palps all the time. A month later back in the ER, was in a fib. Was chemically converted and admitted to hospital. Echo and stress test were fine. Doctor put me on sotolol and I was fine for a week then started into bigemeney again. Took me off sotolol and put me back on atenolol. As soon as the sotolol was out of my system despite the 50 mg of atenolol my heart was off to the races again, not a fib but tachycardia, pacs, pvcs. It was like it had just quit working for me. Has anyone had a similar experience or heard of meds just not working anymore? Mostly just curious....doc put me on bystolic and that works much better for me now.