I have a 4cm ascending aortic aneurysm at what size does it need to be repaired?

5.5 -6.0 cm: Other factors are important: valve leakage( aortic regurgitation) increasing size or pain hypertension( high blood pressure) other cardiac or vascular, or lung disease other significant risk factors for a major operation in general, ct follow up about every 6 months until > 5.5.

5-6 cm: Generally, these are fixed when they get to be 5-6 cm in diameter; however, other factors may apply, such as presence of a congenital condition such as marfan's and whether the aortic valve is diseased. You should discuss this with a thoracic surgeon who has experience with this type of repair.