Hi there, I’m sorry you lost your mom to a brain aneurysm. From what I understand a 4.0 ascending aorta is not of particular concern for rupture based on size alone for immediate risk but it should be monitored at least annually for growth. I have read that sizes under 4.5 cm risk of rupture is pretty low at around 1%. Since my mom and sister both also have dialated ascending aortas I plan on asking my cardiologist about genetic testing to see if we have some familial condition that would put us more at risk for early rupture. My grandfather on my mother’s side also suffered from a ruptured brain aneurysm and died from it at age 65. He had a long history of smoking and drinking and had suffered a stroke that left him disabled many years before that however. Best thing to do is to bring your family history to your doctors attention and ask for genetic testing and keep monitoring the size of your aorta with periodic scans. Wishing you good health!