Yeah it's been a long time, but I remember Durito mentioning some of this stuff in early days of GL
I'm not sure about how rare it is. I would have guessed that Thoracic are more common than abdominal, but googled and saw what you said. Abdominal are more common. I guess that make sense..
so the Ascending portion of the Aorta is very short. Whereas the Descending part that curves downward and breaks off at your hips into each leg is longer..... so maybe more opportunity for issues there? I'm really out of my league with speculating on that stuff. I only spent time researching what I was dealing with. and I'm rusty on that, as after I figured out that I could function same as ever, I stopped actively reading on it.
since my diagnosis, I've run my fastest adult 5 and 10ks and done multiple 3-5 night 40+mile hiking and camping trips.
so it doesn't have to slow you down