Magnesium Deficiency- Rapid Heart Rate?

So I went to the Dr. & she noticed I have a rapid heart rate. She recommended I see a cardiologist, which I am. But I also had some bloodwork done. Everything turned out normal, but my Dr. said that my magnesium levels were on the low side (although still in normal range) & that I should take supplements to see if this could be contributing to my heart rate. What's kind of weird is that awhile back I had migraines & then panic attacks...which are also thought to be perhaps related to magnesium deficiency. Anyone had a similar experience? Or know anything about this whole topic?