I also had similar symptoms. Like so many other women, I went through every cardiac test available and nothing was wrong with my heart. I do have a damaged thyoid gland from what I believe is an autoimmune response to the silicone in the Mirena. I'm glad you're getting your thyroid tested because many women develop this problem. The Mirena IUD is costing the health system lots of money by so many women needing expensive cardiac, neurological, and various other testing, not to mention treating so many psychiatric and physical side effects. You can do a search in this forum for specific side effects and find out you have lots of company with your symptoms. I hope you plan to have it removed. Many women don't have the side effects until they've had it for years.