Ate foods high in sat, and trans in childhood, but changed early teens, and eat healthy now.could the diet have caused irreversible progression of ath?

It was a timely chan: You are smart to have made a change to healthy eating, well in time. Most people do not realize this until they are in their 50s. Then it is too late. Since it takes more than 10 years to develop ath, you should be fine, and any damage done is reversible provided you eat healthy in the future and exercise regularly through your adult life. Good luck.

Doubtful: You are young enough to care for your body for a long time. Any atherosclerosis you may have as described, should be reversible with good diet, exercise and eating habits. Best to you... glad you took notice