They are definitely hormone related. My arrythmia began when I had norplant, but connection wasn't made at the time. They continued with Mirena. Since removal, I get them during the very end of and the first few days of my cycle, when both estrogen and progesterone are low. I also get shortness of breath. I am healthy otherwise, run 10-15 miles a week when I am not training. Other than the mirena weight gain, I am not overweight. In fact, most people think I am crazy to want to lose the 20 lbs I have left to lose. So it's not an issue of unhealthy lifestyle factors.
Where are you in your cycle?
Be well!