I don't know that this is what your problem is, but potassium levels can affect your heart rythym.
http://www.merck.com/mmhe/sec12/ch155/ch155k.html
What is your replacement dose, what is your ACTH, and yeah, they are idiots - of course, something that just effects everything is not of consequence eh...
I travel 6 hours (one way) for competent docs - quarterly - just to get managed - so you may want to think of doing so.
When was your last dexa scan? Vitamin d levels? etc etc? There could be other issues - and steroids do rip up the body - you need to be watched carefully for damage and for changes to other hormones. I would advise finding a better doc myself - it is tough to do!
Thanks for your comment and questions. I am currently taking Hydrocortisone and Florinef along with extra salt. I also take Synthroid and Cytomel for hypothyroidism.
Well I can't say I'm under a competent endo, I've been to all there are in the area, which comprises 2 different offices. I would have to travel hours away to get to any others. It seems their favorite phrase is "well, that's not related to Addison's Disease", which seems ironic since the adrenal glands affect so many different systems in the body. In reality, these doctors seem to mainly specialize in diabetes, which I don't have.
But in answer to your question of testing for renin, aldosterone, sodium and potasium levels, I am not sure that that has been done recently. However my cortisol levels were tested recently and were where they should be.
It could be from the long term steroid use. What steroid have you used, as well have you added florinef which helps support the salt retention, and would help your heart? I also take salt daily under the advisement of my cardiologist since my BP is chronically low with my florinef.
You may also need to know your renin, aldosterone, sodium and potasium levels pretty frequently. Have you been followed closely by a competent endo? Do you test your cortisol levels at all?