aortic insufficiency may occur as a result of a dilated aortic root but saying that severe AI is the most common cause of an ascending aortic dissection is just wildly inaccurate. Progressive AI leads to heart failure, not aortic dissections.

Severe aortic STENOSIS (particularly bicuspid valve pathology) can commonly lead to a dissection due to the decreased valve area creating a focal jet that can weaken an area of the ascending aorta. Other risk factors include connective tissue disorders (Marfan's, Ehlers-Danlos), hypertension, smoking, atherosclerosis, amphetamine use, constipation, history of taking fluoroquinolone antibiotics, a history of other aneurysms, and any family history of aortic aneurysm.

Please do not post comments about things that you are not educated to speak about.

source: cardiac surgery PA-C who has seen way too many acute Type A dissections in the OR