What is benefit of ICD with EF of 30-35% three months after quad bypass

[Prokuski]

Three months ago, my husband (57 years old) had heart attack with emergency quad bypass.  After the surgery, and again after 3 1/2 weeks, the echo showed EF 30-35%.  All has gone remarkably well with recovery, however, he has been wearing the life vest because of the lower EF.  Now, after this week's echo (at 3 months), it shows no improvement, still EF 30-35%.  Cardiologist says now he should have internal defib inserted.  We are concerned about the benefits vs. any limitations he may have.  And, we are questioning whether or not the EF can increase to that magic number of 36% affording him the ability to not have it implanted at all.  We asked questions, received answers, need to have consult with the electro cardio guy, but would like another opinion.  Could waiting until 6 months out have any effect on the EF rising or is it about where it will be at this point?  Any thoughts?  All my husband wants to do is get back to work...plumber...so that he can return to some normalcy in his life and he cannot do it with the life vest as it is cumbersome and is a safety risk for his job.