Can I move out-of-state if a grandparent visitation is already set through court?

The grandparents usually are not the ones in this equation.

The issue in relocation is whether the other parent approves, and if the other parent disapproves, then this is an issue before the court.

Call me with any questions.

The rights of grandparents to visit with their grandchildren is a rapidly expanding field of law.  Once a visitation schedule has been established, it must be modified like any other visitation schedule.  You need to file a new "Complaint for Modification" in the courts. That means that you will need to get the court's permission to leave. Your state may require and "application to relocate" and the grounds differ from state to state, but usually a substantial change in circumstances is necessary.

As for continued visitation, if the court allows you to move then they may modify the visitation to longer visits - like weekend visits rather than one a week - or whatever is prudent under the circumstances.  You should seek legal help with this and see if your attorney can negotiate for you with the Grandparents before you request modification so that things go more smoothly.  Good luck.