About assessing the risk of not taking statins: As I said, the exam you're about to take is only able to give you positive answer (yes, your carotid is sclerotic), not negative (won't say: no, your coronaries or the rest of your arteries are not sclerotic), so it's sort of useless.

What I'm still wondering is how a familial hypercholesterolemy would have been missed during earlier blood tests? It's a pretty standard test here, and 7.8 and 10.3 are extremely high for a fit person.