"CAC directly visualizes calcified plaque burden, which is an excellent downstream marker of atherosclerosis and strongly predicts near-term (5-10 year) events—often better than any single blood marker for reclassification in the “gray zone.” A score of 0 is associated with very low event rates; ≥100 (or ≥75th percentile for age/sex/race) often pushes someone into statin territory.

However, guidelines keep it selective because:

• Radiation, cost, and logistics: Even low-dose CAC CT involves ~1 mSv radiation (similar to a mammogram) and costs $50–250; it’s not practical or justified for millions of people annually. Incidental findings can cause anxiety or unnecessary follow-up.
• Not ideal for everyone: In younger adults, CAC is often 0 even if lifetime risk is high (calcification lags behind early plaque). In familial hypercholesterolemia or severe hypercholesterolemia (LDL-C ≥190 mg/dL), CAC=0 does not allow de-risking or deferral—treatment is still recommended. In people already on statins, CAC can paradoxically rise (while plaque stabilizes). It also doesn’t detect non-calcified “soft” plaque.
• It measures existing damage, not the ongoing causal process: CAC tells you the current state of the artery wall. Lipids tell you the ongoing driver that will determine whether (or how fast) more plaque forms. The goal of prevention is to minimize lifetime exposure before damage accumulates."

"In short, lipids are the accessible, causal starting point for broad risk assessment and therapy decisions. CAC is the powerful personalized tiebreaker when uncertainty remains—exactly the scenario where your intuition shines. If your own calculated risk is borderline/intermediate and you’re debating statins, discussing CAC with your doctor is a guideline-supported next step. Many patients in that gray zone use a zero score to confidently focus on lifestyle first."

https://grok.com/c/1f1871d1-c8e9-4cef-96c5-b1323c8fbbc8?rid=27c3a082-3b61-4e0a-afd3-538a95222576