I don't think anxiety can cause death unless there are some serious underlying health problems e.g. very serious heart disease, extremely high blood pressure, aneurysms etc. and that is just a possibility. I was given Inderal at one time in an attempt to slow my heart rate. My doctor was looking at the future more than the present. A heart has only so many beats in it to last a lifetime and I was using up a lot of mine
BTW I also had arrhythmia and pulmonary hypertension at the time. 20 years later and I'm still here
I'd tell you to relax but I've been there. Telling someone with fullblown anx to relax is kinda like telling someone on fire to chill out
Hang in there... it can get better and very likely will.