A scheduled cath is better than an urgent cath
Prayers certainly...
But to be on the SAFE side, have her take it easy and not exert until she has the cath test.
Sometimes a heart won't seem as bad as the cath test shows it to be.
I know this from personal experience.
My symptoms weren't bad, but the cath study showed me to have a 99% blockage (among a total of 4) right after the "widow maker" area.
My heart was a time bomb and they wouldn't let me off the gurney after they saw my cath results, and I had emergency quadruple bypass the next morning.