What is the prognosis for Stage 4 heart failure?

The stage describes how severe your heart failure is. It's usually given as a class from 1 to 4, with 1 being the least severe and 4 being the most severe: class 4 – you're unable to carry out any physical activity without discomfort and may have symptoms even when resting

https://www.nhs.uk/conditions/heart-failure/diagnosis/

How long can you live with Stage 4 congestive heart failure?

Although there have been recent improvements in congestive heart failure treatment, researchers say the prognosis for people with the disease is still bleak, with about 50% having an average life expectancy of less than five years. For those with advanced forms of heart failure, nearly 90% die within one year.

https://www.webmd.com/heart-disease/heart-failure/news/20080603/heart-failure-patients-too-optimistic

Is there any chance of surviving Stage 4 cancer?

Science/Medicine has not found a way to cure cancer once it has reached Stage 4. Medicine has come a long way as far as treating Stage IV cancer, but you will find researchers/oncologists/specialists/etc. will not come out and say that Stage IV cancer can be cured.

https://www.verywellhealth.com/stage-4-cancer-5092070

What is your life expectancy with Stage 4 cancer?

There is no average stage four cancer life expectancy which is relevant amongst all types of cancer. Some cancers, such as pancreatic cancer, have a very short expected survival rate while others, such as testicular cancer, may have a high survival rate. Many patients who are diagnosed with stage four cancer will not live one year.

https://www.verywellhealth.com/what-is-stage-4-lung-cancer-life-expectancy-2249420