Hello Madrid,
Heart palpatations are common in menopause and, and far as I am aware, are confined to a particular phase, so should pass.
Magnesium is a muscle relaxant and the heart is a muscle. It's certainly worth trying. Mindfulness also helped me as palpatations adds to stress which in turn make them worse.
If you are particularly worried, go and see your GP. Often when other things check out ok the palpatations ease anyway.
Hope that helps.