Magnesium Citrate or Malate 300mg started helping and stayed helping for around a year, at some point I stopped and the anxiety never came back, knock on wood, 2 years later.
I also had help with Taurine, and Pharma GABA (a version of GABA), and occasionally 5-HTP.
Personally, I found that Calcium made Anxiety worse, as did high dose Vitamin D (strange, I know - though it can lower Magnesium), Gluten / Dairy, High-Histamine containing foods and FINALLY vitamins B12 and Folic Acid (known to increase Histamine).
I am absolutely sure that those things caused anxiety and those other things reduced as I kept a VERY detailed journal for 2 years and stopped/started many times to confirm, and I was extremely careful to only add one supplement at a time to be sure.
Years later, I can take Calcium (regular dose, I'm fine - too much and I don't feel great), The B-Vitamins are no longer an issue UNLESS I take very high dose Folic Acid. And I've stayed of gluten / dairy as I know the cause of my AF is due to a long term stomach infection - which took years to diagnose. It truly inflames my GI tract and causes alot of the secondary issues.
Anyway, to sum it up, the anxiety I have not felt for years now due to those things.