I was diagnosed with PSVT (back then it was PAT) a long time ago...maybe 25 years or longer? I had occasional episodes of tachycardia, out of the blue, sometimes when I was just relaxing and reading a book. The first time I thought I was having a heart attack.

I wore a holter monitor for a day or two, if I recall. Anyway, the doctor and I agreed that if it became debilitating I would start medication (can't remember what kind) but she told me that sometimes the side effects of the meds were worse than the symptoms if it's a mild case.

I still have an occasional episode, maybe only a half dozen a year, if that. And I can't sleep on my left side; doing so virtually always triggers tachycardia. It's a creepy feeling and I don't like it, but it's infrequent and the docs assure me it's not life-threatening, so for now I don't take anything for it. Just talk myself through it: "This will pass, it's not a heart attack, you'll be fine, take deep breaths..."