271EMF Advancing Emergency Department Chest Pain Risk Stratification With Monocyte Chemoattractant Protein-1 and High-Sensitivity Troponin

Abstract

The History, Electrocardiogram, Age, Risk factor, and Troponin Pathway (HEART Pathway) risk stratifies 50-55% of emergency department (ED) chest pain patients as non-low-risk and recommends that they receive observation and stress testing. The objective of this study was to determine if two novel biomarkers, MCP-1 and hs-cTnT, alone or in combination, can achieve ≥ 99% sensitivity and negative predictive value for 90-day MACE among non-low-risk HEART Pathway patients. A case-control study was nested within a multicenter, prospective study (STOP-CP). ED patients ≥ 21 years old who presented to the ED with symptoms concerning for acute coronary syndrome who had a HEAR score ≥ 4 or known coronary artery disease (CAD), a non-ischemic ECG, and non-elevated contemporary troponins at 0- and 3-hours were eligible for inclusion. Cases (N=40) were patients with 90-day MACE events (all-cause mortality, myocardial infarction, or revascularization). Controls (N=179) were patients without MACE who were selected based on frequency matching using age, sex, race, and numeric HEAR score or the presence of known CAD. Receiver operator curves were used to assess biomarker performance at various cut-points. Sensitivity and specificity were calculated. The prevalence of MACE in non-low-risk patients in the STOP-CP study was 6.5% (40/618). This was used for determining negative predictive value (NPV) and positive predictive value (PPV). Among the 40 cases and 179 controls, there was no significant difference in age (p=0.90), sex (p=1.00), race (p=0.91), or HEAR score/presence of CAD (p=0.89). An MCP-1 cut-point of 194 pg/mL resulted in 50.0% (95% CI 33.8-66.2%) sensitivity and 93.1% (95% CI 90.5-95.0%) NPV for 90-day MACE. A MCP-1 measure of 238 pg/mL had a 30.0% (95% CI 16.6-46.5%) sensitivity and 93.5% (95% CI 92.0-94.7%) NPV. A hs-cTnT result of 11 ng/L was 60.0% (95% CI 43.3-75.1) sensitive with a NPV of 95.7% (95% CI 93.8-97.1). At a hs-cTnT cut-point of 19 ng/L, sensitivity was 30.0% (95% CI 16.6-46.5%) with a 94.5% (95% CI 93.3-95.5%) NPV. These data suggest that MCP-1 is not a useful biomarker for risk-stratifying ED patients with non-low-risk chest pain. Hs-cTnT may be a useful biomarker for enabling additional patients to be classified as low-risk and discharged without lengthy evaluations.