Age-Dependent Efficacy of Incidental Coronary Artery Calcium on Pre-CAG Chest CT: Potentially Missed Prevention Opportunities in Chinese Population

The 2026 ACC/AHA Multisociety Dyslipidemia Management Guideline emphasizes the clinical utility of coronary artery calcium (CAC) and recommends integrating incidental CAC from non-ECG-gated chest CT into cardiovascular risk-stratification workflows; nevertheless, such incidental findings remain substantially underutilized in routine clinical practice. Many young-to-middle-aged patients present with acute myocardial infarction as their index cardiovascular event, even though prior chest CT could identify CAC that would trigger statin-based primary prevention. This single-center retrospective observational study enrolled 976 patients undergoing invasive coronary angiography (CAG) who had non-ECG-gated chest CT within the preceding 1 year (2020–2025) to assess cross-sectional associations between incidental CAC burden and angiographic coronary stenosis. CAC burden was categorized as Grade 0–3 using the validated Shemesh ordinal scoring system, with 79.2% of participants being CAC-positive. CAC positivity and obstructive CAD prevalence increased progressively with age. CAC positivity was associated with higher conditional odds of obstructive CAD among younger individuals, while this conditional risk signal was attenuated in older adults. CAC grade showed a step-wise positive correlation with stenosis severity. Following adjustment for age, sex, hypertension, diabetes mellitus, dyslipidemia, and smoking status, CAC was identified by multivariate regression as the strongest independent predictor of obstructive CAD (OR = 11.732, 95% CI: 7.700–17.875, p < 0.001). Among CAD patients, CAC-negative subjects had higher diabetes prevalence, in keeping with the propensity for non-calcified vulnerable plaques in diabetic individuals. Incidental CAC on routine chest CT represents a robust age-modulated biomarker for obstructive CAD, and considerable primary-prevention opportunities are missed in Chinese patients referred for CAG. Opportunistic age-stratified CAC screening assisted by artificial intelligence may improve real-world cardiovascular primary prevention.