Heart failure is a serious condition -- but it's also one that can be treated with considerable success. I don't like the term "end stage" because many patients improve even
if their overall heart function is poor. I've had patients who were labeled this way who have done well for years.
Also, heart failure can wax and wane. A person with heart failure can have periods of worsening symptoms that require hospitalization, perhaps as a result of not taking all of the prescribed medications correctly or not following a low-sodium diet. But with increased therapy, she might improve enough to go home.
In some patients, however, the heart may not be able to pump adequate blood to vital organs. This can result in kidney failure, severe shortness of breath after limited activity, and even reduced mental status.
I'd recommend a consultation with a cardiologist to make sure your mother is receiving all of the medications that have proven to be helpful for this condition. And make sure you take the time to talk to your mother about the future. Ask her about what she wants done if her heart failure worsens to the point where treatment is no longer effective.