How risky is a pacemaker and cables replacement procedure when the cables are 13 years old?

It depends: If they are only replacing the pacemaker and leaving the old wires alone, not very risky. If they are going to remove the old wires there is additional risk, although many centers are quite good at that. Not every place that puts in pacemakers is set up to remove old wires. Discuss this with your physician.

Extraction question: It depends on whether they're just adding new wires or taking out the old ones. Those 13 year wires are socked in there pretty well and secured by scar tissue and calcium deposits (essentially, limestone). We can usually get them out with a risk < 2% of major problems, but not always. Sometimes we have to leave a piece behind.