Brai atrophy and frontal lobe dementia

My husband, 61, has end-stage congestive heart failure (ejection fraction 12). He has also been diagnosed with brain atrophy (and resulting increase in the fluid in the brain), described in his medical reports as "prominent frontal lobe atrophy", apparently caused by insufficient blood supply to the brain. My question is: Does frontal lobe atrophy result in frontal lobe dementia, and how fast is the progression of this disease? It seems obvious to me that he has already developed mild dementia, he is forgetful and and sometimes have problems following a normal conversation. What can I expect in this situation?