Abstract 12580: Impact of Zero Coronary Artery Calcium on Downstream Cardiac Testing

Abstract

Introduction: While coronary artery calcium scoring (CAC) has emerged as a useful tool for cardiovascular disease (CVD) risk prediction, its impact on downstream resource use remains unclear, especially in those with zero CAC. The purpose of this study was to determine the relationship between zero CAC and downstream use of cardiac procedures. Methods: Consecutive CAC scores from two academic hospitals in Toronto, Canada, from 2011 - 2019, were linked to population-based databases. Subjects with zero calcium without previous CVD were subsequently propensity score-matched with a non-CAC-tested control group for age, sex, CVD risk factors and comorbidities relevant to receipt of testing. Downstream cardiac testing, myocardial infarction (MI), stroke, and congestive heart failure (CHF) hospitalizations were compared between the two groups. Results were analyzed using descriptive statistics and Cox proportional hazards regression models. Results: 4,884 patients (Mean 56.8y, SD 11.3) underwent CAC scoring, of whom 2,709 (55.5%) had zero CAC (Mean 52.9y, SD 10.6, 55.4% women). Compared to those not tested at 90 days, zero CAC subjects had similar graded exercise stress test (GXT) (72 tests vs 60, p = 0.29), stress echocardiography (40 vs 32, p = 0.34) and myocardial perfusion imaging (MPS) (26 vs 37, p = 0.15), but higher cardiac MRI (CMR) (48 vs 7, p < 0.001) use. At 3.4 years, GXT (HR 1.24, 95% CI 1.14 - 1.35), stress echocardiography (HR 1.80, 95% CI 1.59 - 2.05) and CMR (HR 3.40, 95% CI 2.55 - 4.53) use was higher in the zero CAC group, whereas MPS (HR 1.08, 95% CI 0.97 - 1.21) and catheterization (HR 1.14, 95% CI 0.91 - 1.44) were similar and PCI (HR 0.59, 95% CI 0.35 - 0.98) and CABG (HR 0.14, 95% CI 0.03 - 0.61) were lower. There was an approximately 5-fold lower rate of MI (HR 0.22, 95% CI 0.10 - 0.51) in the zero CAC group at 3.4 years and no difference in stroke (HR 0.98, 95% CI 0.46 - 2.05) or CHF hospitalizations (HR 1.15, 95% CI 0.53 - 2.48). Conclusion: Zero CAC was associated with higher use of some non-invasive cardiac testing, similar use of catheterization, and reduced PCI, CABG and AMI when compared to a propensity score-matched control group. The results support the utility of a zero CAC in limiting invasive procedures while maintaining an association with reduced cardiac events.