If the arota of the heart is damaged, which function of the heart will be affected first?

Coarctation of the aorta can cause high blood pressure in the heart. This can cause the muscle of the heart's main pumping chamber (left ventricle) to become thick. Eventually, the function of the heart muscle could deteriorate if the condition isn't treated.

if the aorta of the heart is damaged, the function of the heart muscle could deteriorate

Explanation:

If aorta is damaged then aortic dissection most often happens because of a tear or damage to the inner wall of the aorta. Chronic high blood pressure may stress the aortic tissue, making it more susceptible to tearing. About 20% of patients with aortic dissection die before reaching the hospital. Without treatment, mortality rate is 1 to 3%/h during the first 24 h, 30% at 1 wk, 80% at 2 wk, and 90% at 1 yr.