@Drew944 If you had an echo for one of the measurements you list and the CT for the other, it is possible the size of the aneurysm hasn't changed and it is actually correctly measured at the smaller size. One test measures straight across like a ziti is cut and the other measures on the bias, like how a penne pasta is cut on the angle. So your aneurysm might have been the 4.3 measurement all along and it is stable. Aneurysms don't get smaller as much as we wish they would. But the difference in the testing and the person reading the results can result in different numbers.
@anniejam Did your cardio indicate it would be "open heart surgery" or open chest surgery? As far as I know, the aneurysm is located either ascending from the heart or descending from the heart and during repair, the heart itself isn't surgically involved. I also have the AAA but have a leaky aortic valve as well which, if one or the other needs repair will result in both being repaired at the same time and I guess that would qualify as "open heart surgery".

When I was first diagnosed I have to say that it was the only thing I could think about for about a year. But the initial horror of the diagnosis has faded and it has been 10 years and no symptoms so my advice is don't let this diagnosis steal your enjoyment of life. Follow your cardio's orders and get regular testing to monitor the size and if it is growing.