I agree with @Adirondackwannabe. What exactly are the doctors suspicious of, and worst case scenerio what is the treatment and prognosis. Heart matter frequently are treatable. Although, of course it is very understandably scary for you and your mom.
My dad had heart bypass at the age of 46, when they went to use his mammory artery it was two blocked and so they had to go to the leg vein to add the bypass around the heart arteries. It confirmed he was blocking up everywhere probably. The doctor told us he would likely have problems again within in 10 years because people who are this blocked in their arteries this young just gather up the stuff too readily. Anyway, after bypass he was like new. He had never suffered a heart attack, he went to the doctor because of shortness of breath symptoms, so his heart was strong. He is 68 now. He does have some slight symptoms the last few years, leg pain, and he did have to have one of the major arteries in his neck closed off because it was so blocked, but basically he is really good.
I could tell you many stories of heart problems being resolved or lived with for many years without major difficulty. Of course I don’t know your mom’s specific situation. And, also stories of suspected heart trouble winding up to be nothing major at all.
I remember one Q a woman’s mom had to go through a heart angiogram, and I gave my usual argument it was her thyroid, she was a graves disease patient, and extremely overmedicated. They thought for sure her heart angio would show something. It was completely negative, and they determined it likely was her thyroid way out of control.