Good question. I have a 4.5 cm aneurysm (age in mid 60's) and I worry about the same thing. Everything I've heard or read indicates that it depends on the patient's wellness. So it's a patient-by-patient decision (with doctor variability thrown in there too).

I'm handling it by trying to improve my capacity to handle a multi-hour surgery. My HBA1C is currently normal, but I monitor my glucose on occasion to see how it's trending. I'm trying to improve my aerobic fitness, especially longer sessions. Eat right, keep BP low by monitoring it and taking the BP pills. ...

It's perfectly reasonable to ask the physician that's monitoring your aorta what they look for when deciding whether a patient has the capacity for an open heart surgery and how you can get there if you aren't already. To my medically uneducated understanding, there's some early stage work on repairing these without open heart surgery. Sounds like it's a fair ways away. Yet something to tuck in your hat, so to speak.

If you haven't mentioned the PMR to the person monitoring your aorta (and/or the aneurysm to the person monitoring your PMR), I would. I had PMR when I was diagnosed with the aneurysm. I learned there's a related disorder Giant Cell Arteritis that's associated with aneurysm. Best if both your doctors know both conditions.

Hopefully you and I both will never need an intervention. Wish you all the best!