The FAA is very progressive with regards to heart issues. They are mostly concerned about conditions which can lead to sudden incapacitation.
Also MVP is a very frequently mis-diagnosed condition.
My suggestion would be to talk to AOPA medical, get a full cardio workup, then work with an AME who knows the info you need before hand. Have the package ready to go with everything you need and expect a few weeks for an FAA decision. At worst you will likely operate under special issuance. At best, FAA will clear you unrestricted once they review your paperwork.
In the meantime, be careful with supplements. Magnesium is good, but too much throws out the balance with the other electrolytes which can cause issues.