Good to know! The main concern I have is that my blood pressure typically runs low (when I'm not having a sustained bout of SVT or a big panic attack) and beta blockers lower blood pressure. I have also heard from people who take them that they can cause fatigue and depression, which are the last things I need.

I asked the doctor if I could take Metoprolol as needed and the doctor said I could give it a go but that I'd likely get better results if I took it every day.

Ironically, my heart rate also typically runs low - in the low 50s when I'm at rest. So that's another concern. I really need something I can take just when I'm having a bout of SVT. But there doesn't seem to be anything for that.