Brain atrophy and dementia?

My husband, 61, has been diagnosed with "prominent frontal lobe atrophy" of the brain, due to insufficient blood supply to the brain caused by congestive heart failure. Question: Does frontal lobe atrophy lead to frontal lobe dementia, and if so, how fast does it develop? I am aware that this is a question for his physician, however, I have not received any straight answers; I have a feeling it is out of concern not to upset me, however I would like to get as much information as possible. Any information would be most welcome. Thankyou