The Role of Biomarkers for Coronary Artery Disease Detection in an Australian Rapid Access Chest Pain Assessment Clinic

<b>Background/Objectives:</b> The Rapid Access Chest Pain Assessment Clinic (RACPAC) streamlines the evaluation of low-to-intermediate risk chest pain and helps avoid unnecessary hospitalisation. Biomarkers {low-density lipoprotein cholesterol (LDL-c) and high-sensitivity C-reactive protein (hsCRP)} are established cardiovascular risk markers. Yet, their diagnostic value for stable coronary artery disease (CAD) in RACPAC remains uncertain. Therefore, we aimed to determine the utility of biomarkers in predicting the presence of CAD in the RACPAC setting. <b>Methods:</b> A retrospective cohort study of consecutive adults attending RACPAC between 2012 and 2021. Multivariable logistic regression and receiver operating characteristic analyses, including prespecified subgroup and sensitivity analyses, were used to evaluate the predictive value of hsCRP and LDL-c for the presence of CAD detected on CT Coronary Angiogram (CTCA) or Treadmill Stress Echocardiography (TSE) as the primary outcome. <b>Results:</b> 3569 patients were included in this study, the mean age was 55.4 ± 11.3 years, and 48.8% were female; 37.4% had hypertension, while 39.5% had dyslipidemia. The mean LDL-c was 3.1 ± 0.9 mmol/L, and the median hsCRP was 1.9 mg/L (IQR 0.9 to 3.8). The regression analysis for the primary outcome showed that neither hsCRP nor LDL-c predicted CAD on CTCA (hsCRP OR 1.00, 95% CI 0.99 to 1.02, <i>p</i> = 0.70; LDL-c OR 1.16, 95% CI 0.97 to 1.39, <i>p</i> = 0.11). On TSE, hsCRP was not associated with CAD, while LDL-c showed an inverse association with CAD (hsCRP OR 0.98, 95% CI 0.83 to 1.00, <i>p</i> = 0.78; LDL-c OR 0.44, 95% CI 0.21 to 0.87, <i>p</i> = 0.02). ROC analysis showed AUC 0.553 for log hsCRP (95% CI 0.501 to 0.606) and 0.508 for LDL-c (95% CI 0.450 to 0.566), with <i>p</i> = 0.2756. <b>Conclusions:</b> In a large real-world RACPAC cohort, neither elevated hsCRP nor LDL-c predicted the presence of coronary artery disease in the rapid access chest pain clinic (RACPAC) cohort. In contrast, CT coronary angiography (CTCA) demonstrated superior diagnostic accuracy compared with treadmill stress echocardiography (TSE) in this setting.