My Cardio prescribes Magnesium quite often for PVC's. I started using it after 13 months of 10,000 to 25,000 etopics a day and it was a miracle mineral for me.
Give it some time though, it takes about 6 weeks to build up at a cellular level and thats usually when you really see an improvement!
I take about 500 to 600 mgs. to begin with and always use liquid or gluconate as it is more readily absorbed. My Cardio prescribed mag oxide but after some extensive research, he agreed that oxide absorption is lower with only 20 or so percent. Liquid and gluconate offers a chance at about 80% absorption.
Hope you see some results!