Could chelated magnesium be used for tachycardia as an alternate to atenolol? and how much per day? heart is fine due to benzodiazepine withdrawl.

Best talk to MD: Medications we give like atenolol have limits, i.e., the heart rate and blood pressure. Chemicals or nutrients even have no limits until they are toxic. If you use magnesium, you can only know the extent of maximum dose when you develop toxicity and you don't want that. It is best to talk to your md about amounts of medicines you take.

Possibly: Magnesium often helps tachycardia; whether it can be an alternative to atenolol for you is impossible to know until you try it, but if not a complete alternative it may allow you to reduce your atenolol dose. I advise magnesium taurate or glycinate with 400-800 mg of magnesium; if you take more than you can absorb you'll get loose stools, in which you can cut back.