What size thoracic aortic aneurysms should be repaired?

• > 5 - 6 cm for ascending aortic aneurysm
• > 6 - 7 cm for descending aortic aneurysm
  
• > 7 cm in high risk patients
  
• consider repair at smaller size if: presence of symptoms, accelerated growth rate (> 10 mm per year)

Source

Woo, J. MD and Mohler, E MD. "Management and outcome of thoracic aortic aneurysm" Up to Date. 28 Jan 2009.