I was researching similar functionality and the solution depends on whether you want to disable events alltogether (if nodeX is down) or create actions depending on the events.
In both cases you will probably need a way to determine what nodes are affected by nodeX status and which are not.

Basically if you want to influence if events start at all - modify appropriate rule in Event Processing Policy. To influence actions based on the events and let script decide what to do.

In my case I modified Event Policy to send e-mail only if superior node is up.
If you want, read this topic Dependency script based on infrastructure.

With regards,

Milan Sperl