Some answers have been answered on your post on the same subject. Your uncle is in heart failure mode with an EF below 29%. The stages of heart failure start with very little symptoms but usually some chest pain and treated with medication, etc. There are 3 other stages and the last stage is the patient is unable to do very little without being out of breath, lung edema (fluids) causing dry choking cough, etc. That would be the final stage and therapy isn't very helpful. The heart failure will cause cardiac arrest.
How critical is the stage depends on your uncle's symptoms, and how well he responds to treatment. Take care