I know someone much younger that had 2 and neither of them worked. Aren't the meds controlling the tachycardia?
I depends on the cause as to whether meds are the best option. Mine was caused by an extra electrical pathway in my heart. The cardiologist said I could try beta blockers, but they must be taken continuously and have side effects. He said the ablation was pretty much a sure cure for my condition. I was against it at first, it sounded too extreme, but looked into it more and decided to go for it.
Patients can have a "quiet heart" on the day of the procedure, and the electrophysiologist might not be able to trigger the problem, and so can't identify the troublesome area in the heart. That's one of the reasons why an ablation might not work. Twice, though, would be very unfortunate. Maybe there's a different cause there that's not so easy to treat.