Opportunistic Screening for Coronary Artery Disease: An Untapped Population Health Resource

Coronary artery disease (CAD) is the leading cause of death in the United States. At risk asymptomatic adults are eligible for screening with EKG-gated coronary artery calcium (CAC) CT, which aids in risk stratification and management decision-making. Incidental CAC (iCAC) is easily quantified on chest CT in patients imaged for noncardiac indications; however, radiologists do not routinely report the finding.To determine the clinical significance of CAC identified incidentally on routine chest CT performed for non-cardiac indications.An informationist developed search strategies in MEDLINE, Embase and SCOPUS, and 2 reviewers independently screened results at both the abstract and full text levels. Data extracted from eligible articles included age, rate of iCAC identification, radiologist reporting frequency, impact on downstream medical management, and association of iCAC with patient outcomes.From 359 unique citations, 83 research publications met inclusion criteria. The percentage of patients with iCAC ranged from 9 to 100%. Thirty-one investigations measured association(s) between iCAC and cardiovascular morbidity and mortality, and 29 identified significant correlations, including nonfatal MI, fatal MI, MACE (major adverse cardiovascular event), cardiovascular death, and all cause death. Incidental CAC was present in 20-100% of the patients in these cohorts, but when present, iCAC was reported by radiologists in only 31-44% of cases. Between 18-77% of patients with iCAC were not on preventive medications in studies that reported these data. Seven studies measured the effect of reporting on guideline directed medical therapy and 5 (71%) reported an increase in medication prescriptions after diagnosis of iCAC, with 1 confirming reductions in LDL levels. Twelve investigations reported good concordance between CAC grade on noncardiac CT and Agatston score on EKG-gated cardiac CT, and 10 demonstrated that AI tools can reliably calculate an Agatston score on noncardiac CT.A body of evidence demonstrates that patients with iCAC on routine chest CT are at risk for cardiovascular disease events and death, but are often undiagnosed. Uniform reporting of iCAC in the chest CT impression represents an opportunity for radiology to contribute to early identification of high-risk individuals and potentially reduce morbidity and mortality. AI tools have been validated to calculate Agatston score on routine chest CT and hold the best potential for facilitating broad adoption.