Coronary calcium scan: who needs one and what the score means

Atherosclerosis develops inside artery walls. CT detects calcium within established plaque, so CAC measures accumulated disease burden rather than today's cholesterol level.^{See reference 1,See reference 2}

CAC strongly predicts future coronary events and can reclassify risk beyond age and conventional risk factors, but it cannot show whether a specific plaque is obstructive or about to rupture.^{See reference 3,See reference 4}

The value of testing comes only when the result changes an action. If treatment is already clearly indicated—or clearly unwanted regardless of the score—the scan adds little.^{See reference 5,See reference 6}

Guidelines support selective CAC testing when risk-based decisions about preventive treatment remain uncertain.^{See reference 1,See reference 3}

A score of zero is a strong negative risk marker in selected asymptomatic adults; scores above 100 identify substantially higher event risk and usually favor statin therapy.^{See reference 4,See reference 6}

CAC does not prove that screening everyone improves longevity. Its benefit is better targeting of proven prevention, particularly lipid lowering and risk-factor control.^{See reference 7,See reference 8}

CAC sees calcified plaque, not all plaque. Younger people can have non-calcified disease despite a score of zero.^{See reference 3,See reference 7}

Incidental chest findings and a small ionizing-radiation dose can create follow-up tests, anxiety and cost.^{See reference 5,See reference 8}

A high score is not the same as a blocked artery. Routine invasive angiography or stress testing in an asymptomatic person is not supported solely by CAC.^{See reference 9,See reference 10}

Adults with borderline or intermediate estimated risk whose statin decision remains genuinely uncertain.^{See reference 2,See reference 4}

Selected people with strong premature family history or other risk enhancers when the result will change management.^{See reference 5,See reference 7}

People willing to act on the result; testing is low value when neither a zero nor a high score would change the plan.^{See reference 8,See reference 10}