Chelatin helps to remove heavy metals. If you are having tachycardias related to that then yes. Have your doctor do a test on your hair to see if you are showing heavy metal levels.
***By no means am I saying go against dr orders or without his/her knowledge***
But if not heavy metal toxicity then talk to your dr about taking potassium, CoQ10 and possibly ATP. Now having said that, it is important that you and your doctor know the side effects and very possible interactions with your beta blockers, blood pressure medications and other interactions. IT IS VERY IMPORTANT to keep doctor in the process as it could be disastrous with possible medical interactions or even food interactions such as grape fruit.
I would stay away from any type of herbal remedies. There is no regulating, or monitoring of herbs, and when mixed with some medications, can be very dangerous.
People hear Herb or Natural and assume they're safe, and they're not.