At 4.2 the likelihood of rupture is close to 0, your aneurysm is in the “small range”. Surgeons normally won’t consider surgery until the aneurysm approaches 5.0 and above, depending on other factors, like body size, family history, other health conditions, etc

You do have to control your BP, my recommendation is to find a cardiologist who is an aortic disease specialist (not all of them are and it makes a difference) to guide you and monitor you. It is important to monitor growth rate and your cardiologist will do that. Although you are far from critical size, find the best surgeon, someone who has done hundreds/thousands of these type of surgeries, in a major medical center near you and get an initial assessment by him/her also

Also, keep your body healthy, (if you smoke, stop) exercise but do not lift heavy weights or do any exercises that leads you to hold your breath while exerting, your BP rises significantly in those moments. You want your body to be at its best if you ever need surgery.

Mine was repaired at 5.2cm, 2 months after it was found after an MTB accident. I was in good shape and the surgery went as well as it could have, my recovery was fairly quick.

I know it creates anxiety when they first tell you, everyone in this forum has gone or is going through the same. Lots of conversations about how to keep stress down and at the top is to find the right care.

All the best