WDW does not have any specific warning about pacemakers or about electromagnets.
If you look in the disABILITIES FAQs thread near the top of this board, you will find some helpful information in post #3. There is a section of Conditions and Concerns which is in alphabetical order. You will find 2 links to information in the heart disease heading and one about electromagnets further up in the list.
You can also contact the manufacturer of your pacemaker for more information. You may find that they don't recommend avoiding anything because the pacemaker is well shielded or they may have specific guidelnes for you. Even if safe from an electromagnet point of view, your doctor may feel that some attractions are not best for you because of the motion - for example, Rock N Roller coaster has a very smooth ride, but it does some full inversion loops that your doctor may recommend you avoid.
You can find the disABILITIES FAQs thread near the top of this board or follow the link in my signature to get there.