How much is too much?

Gosh I do not have any experience with my mom in those areas (she is pretty healthy, just frail). But it sounds like you have alarm bells going off in your head--you are noticing troubling symptoms after the time when the PT is not there. Have you discussed these symptoms with the ordering doctor? Maybe consider a 2nd opinion. The heart is a muscle and does need exercise, so I do think even a diseased heart would need exercise, but maybe the current PT is too much. Get a professional opinion from someone other than the PT.

I do not understand the statement of the doctor that he says that PT is imperative. I was only 61 when I had back surgery, and because of the bad condition of my back the surgeon never ordered me PT. After a couple of months, I asked him if I could not do some supervised PT in the hospital, because my muscles were getting weaker and weaker and I know that when the back muscles are not sufficient you suffer more back pain. He doubted very much that I would be able to do that, but anyway I got a prescription to go to the PT specialist. He first consulted my file, and said he did not believe that PT would help me on the contrary. Anyhow, I wanted to try it. After about 20 mins, I was a total wreck, difficulties breathing etc. And I have a heart in 100 % sound condition. So the PT specialist said : Stop and don't come back. It is better to leave it this way, than getting more / other difficulties. So in case of your mom, at 86 years, I would certainly get the professional opinion of another heart specialist and a geriatric specialist, instead of continuing the PT. Even the stress your mom will have each time before she starts the PT can be enough to cause heart problems. Never believe a doctor, when you don't feel good with his advise and go further for more information, other opinions, etc.. Wish you good luck and hope your mom will have a comfy life without her PT. Big hug from Belgium (Europe)