David09 - Pacemakers are made of metal, and that’s what security scanners look for. It’s possible you could trigger the scanner by going through it, so you should tell the security people in advance of your condition. They may demand to see some medical paperwork for proof, so always have that handy.
You should also move quickly through the scanner so that it doesn’t interfere with your pacemaker. You should probably choose to have yourself hand-scanned. That would be safer, notwithstanding all of the inconveniences of a “pat down.”