pacemaker interference

why band?

the band is a piece of plastic/metal or leather it's not an active component

so the bands of apple watches would not interfere with your pacemakers any more than other watches bands

of cause if one wears it too tight it I suppose could give blood pressure issues.

Your Apple Watch is very unlikely to interfere with your pacemaker. However the pacemaker might create “extra” beats to interfere with the Apple Watch Heart Rate monitor, and if you have the Watch ECG sensor this is very likely to suffer interference.

In particular the ECG monitor senses the tiny electrical discharges created in your heart. The pacemaker adds a rather larger voltage which will probably swamp the natural signals and give a completely non-natural trace if the pacemaker fires during recording. Not that ECG really matters for you because already having the pacemaker means your cardiac condition has already been diagnosed, putting you outside the scope of approval for the Watch ECG function.