How Can Depression Be Treated While Suffering From Atrial Fibrillation?

My brother had bypass surgery in 2009. He had 4 bypasses. He was recently hospitalized with CHF and atrial fib. Cardiac cath showed no need for stents. 3 bypasses still open ; one closed. He is 78years old and diabetic, Type 2. He has been told his heart is functioning at 30% and 2 meds are keeping him alive, but making him lethargic and sleepy. Told the only recourse at this point is a heart transplant. He is having PT in the home and a home health nurse is visiting. Not on oxygen - readings by nurse are 100%. What is prognosis in terms of quality of life and longevity? How does he avoid depression?