Abstract 4366828: Does Qualitative Coronary Artery Calcium on Prior Chest CT Add to Risk Stratification of Chest Pain in the Emergency Room?

Background: Chest pain patients with moderate elevations of high sensitivity troponins (i.e., between the 99th percentile and what is considered “positive”) benefit from additional risk stratification modalities to improve discharge decision-making. In the present study we evaluated the benefit of adding qualitative coronary calcium (qCAC) from prior routine chest CT to both high sensitivity troponin T(hsTnT) series and determination of the Heart Score (HS) Methods: This single-centre retrospective study analysed 1,500 patients evaluated for chest pain with moderate peak hsTnT (12-51ng/L). Thirty-day major adverse outcomes(MACE) were assessed based on peak hsTnT alone and with the addition of the HS and qCAC on chest CT performed within 5 years of CP presentation. A multivariate logistic regression was performed on patients with available qCAC data (n=1,037) to assess the independent predictive value of qCAC presence, age, and sex. For a more comprehensive model, a sub-cohort of 627 patients with complete data for MACE, qCAC, peak hsTnT, and a dichotomized HEART score (<3 vs. >3) was isolated and Firth’s penalized logistic regression was employed to assess the combined predictive power of these variables Results: The median age of the cohort was 69yrs , 59% were male, 81% had qCAC on review of routine chest CT scans. Dichotomized HS (OR=9.27 (95% CI=2.21-38.86) p<0.001) and qCAC (6.83 (1.57-29.80) p=0.011) were independent predictors of 30-day MACE. The absence of qCAC demonstrated a negative predictive value (NPV) of 99.1% for ruling out 30-day MACE. A Firth’s penalized regression model including peak hsTnT, HS and qCAC was successfully fitted (model p=0.002) and revealed that peak hsTnT was the most robust predictor of MACE (OR 1.05/unit increase, 95% CI 1.02-1.09, p=0.005). A HEART score >3 had borderline-significant association (OR 14.71, 95% CI 0.88-246.19, p=0.061). In this final comprehensive model, the direct statistical effect of qCAC was attenuated (p=0.111) Conclusion: The presence of qCAC on routine chest CT is an independent predictor of 30-day MACE, its absence is also clinically significant, with a high negative predictive value. However, qCAC does not add incremental risk stratification to a risk algorithm including hsTnT and HS. It should be noted that our cohort was older and had high rate of qCAC- further study should examine the incremental benefit of adding qCAC to a risk stratification strategy among younger patients with less prevalent qCAC