I first was diagnosed with AFIB (heart arrhythmia) when I was about 23.
About a year later I got panic attacks out of nowhere! (but it was actually from my afib experiance).
The anxiety/panic attacks where more scary than the AFIB, because it is an unseen, unmeasurable and selfdoubting enemy. I got treatment for the anxiety, and it helped me a lot.
One of the strategies that I use very much is : arresting my thoughts.
I do not allow any thought to come into my brain, it's my brain and I will allow who I want to.
So I "catch" every thought, examen it. If it does not make sence, is evil, scary, or not wholesome for me, I arrest it and take it out of my mind.
I know it sounds crazy! But you must control what thoughts you are thinking and receiving.