I am right in the middle of testing for my 8% premature ventricular beats. My magnesium and potassium were fine and so was my thyroid. There is no proof that supplementing magnesium does anything for menopause symptoms and palpitations. Magnesium can actually cause diarrhea, so people should be careful with it.
Proper medical examinations are the way to go along with a healthy diet and exercise. I have learned from experience, not to self diagnose or medicate with natural therapies that do not have any regulation or even proof that they work.
Anyway, just my thoughts. I am sure many will disagree.