First of all - 74.2 percent ejection fraction happy dance for your hubby!
I am no a physician so I can only share a few numbers with you:
Typical size of the abdominal aorta is 2.0 cm - 3.0 cm ( Remember other factors are taken into account, male, any other diseases, High BP etc.
A medium aneurysm measures between 5.0cm - 5.3cm
If you have an aneurysm that is larger than 5.6 cm or growing rapidly (grows more than 0.5 cm in six months), you'll probably need surgery.
I hope this helps you in some small way. My hubby had the 2 D echo because he had bilateral pneumonia just a bit over a year ago and his EF was 48%. He is on meds but it scares me so keep on talking to us here in the forum. We will help you as much as we can.