I've been down a road similar to the one you are on. I got a CAC test and found I was in the 98th percentile for my age. I was in my early 60's at the time. The score itself was around 600. My arteries were/are older than you according to a research-backed calculator apparently. 🙂

What it meant for me was getting testing to try to determine if there was an actual blockage. The CAC (I think) measures roughly the volume of plaque. If you think of atherosclerosis as crud in a pipe, the same volume of crud could be all along the pipe and not really block blood flow or it could all be in one place and come closer to blocking the flow. And you have multiple coronary arteries. I got a nuclear stress test first and then I also got a CT coronary angiogram. The CT angiogram showed no blockages greater than 50% (where the level at which they may intervene is around 70 I think).

What it has meant for me long term is going on LDL lowering medication (they want LDL < 55), monitoring my diet more strictly, and trying to improve my aerobic fitness. There's no way I know of to "reverse" accumulated plaque, but the progress can be slowed down substantially. They also can't predict if/when/who will have a problem. So you just have to accept it.

Frankly, it's also meant some worry. It was a turning point in my life. There's my life before and my life after the CAC test (the test also revealed a 4.5cm ascending aortic aneurysm). But, it gets better as time goes by. There are lots of comforting thoughts to help one live with it. I'd guess they are very individual.

Good luck. Many people never have a problem even with a high CAC score. I'm doing all I can to be one of those. Your doctor should talk through lifestyle interventions with you. There's lots of information online as well.