potassium high- heart problem?

Hi,
A few days ago I posted about my kitty Meetoo-20 yrs. old. She has crf w/
100ml of sub-Q fluid every day. She's been in hospital since Friday. The
original info I had was that her potassium level was low, and was the reason
for her lethargy and small appetite.
My updated info, straight from the vet's mouth is that her potassium is
*high* at 6.4
5.5 is normal.
Now that she's in the hospital, they have her on IV fluids and have added some
dextrose to draw the potassium out of the blood stream and into the cells. The
vet said with her potassium that high, her heart could stop.
The vet is calling me later this evening to tell me the results of the most
recent blood test.
We wanted to bring Meetoo home tonight as she's been in hospital since Friday.
Has anyone had experience with high potassium readings?
Susan