Coronary Artery Calcium Scoring for Risk Reclassification and Prediction of Hard Cardiovascular Events in Asymptomatic Adults at Low-to-Intermediate Cardiovascular Risk: A Systematic Review

Coronary artery calcium (CAC) scoring has emerged as a valuable tool for cardiovascular risk assessment, yet its role in asymptomatic individuals at low-to-intermediate risk remains an area of ongoing investigation. This systematic review aimed to evaluate the prognostic value of CAC scoring for predicting hard cardiovascular events and its utility in risk reclassification beyond traditional risk models. A comprehensive literature search was conducted across PubMed/MEDLINE, Embase, and the Cochrane Library for studies published between 2000 and 2025. Prospective cohort studies assessing CAC in asymptomatic adults without established cardiovascular disease and reporting hard coronary outcomes were included. A total of eight studies met the inclusion criteria. Across these studies, CAC demonstrated a consistent and graded association with incident coronary heart disease events, independent of conventional risk factors. Higher CAC scores were associated with significantly increased risk, with several studies reporting markedly elevated risk at CAC ≥100, including hazard ratios approaching 4.6 in low-risk populations, while a CAC score of zero was consistently linked to very low short- to intermediate-term event rates. Importantly, CAC improved risk stratification, particularly among individuals initially classified as intermediate risk, with studies reporting substantial risk reclassification and net reclassification improvement values of approximately 0.25. Evidence also suggested that CAC is more strongly predictive of coronary events than stroke, supporting its role as a coronary-specific risk marker. Although the review included only eight studies and demonstrated methodological heterogeneity in CAC categorization, comparator models, and outcome definitions, findings were directionally consistent across diverse populations and study designs. These results indicate that CAC scoring provides incremental prognostic value and may serve as a clinically useful tool to refine risk assessment and guide individualized preventive strategies in asymptomatic adults at low-to-intermediate cardiovascular risk.