No, CAC only tests for end stage calcified plaque which is how your body tries to transform soft plaque. It's soft plaque that first lines your arteries and is capable of rupturing. You might be infested with soft plaque, but if none of it has calcified yet (which can take decades) then you'll have a CAC score of zero.

Using CAC store to gauge risk is like waiting until you have end stage symptoms of any disease before you consider yourself at risk. The ship has already sailed and you should have instead focused on prevention for decades.

The sibling comment is a great example of the misinformation here. They have high cholesterol but a CAC score of zero gave them the peace of mind to not use statins.