Objectives: To test novel markers of acute coronary syndrome (ACS), monocyte chemoattractant protein-1 (MCP), myeloperoxidase (MPO), C-reactive protein (CRP), and brain natriuretic peptide (BNP) in low-risk emergency department (ED) patients who were evaluated for ACS in a chest pain unit (CPU).
Methods: A convenience sample of 414 patients underwent CPU evaluation, including provocative testing, and were followed prospectively for 45 days for ACS, which was defined as death, myocardial infarction (MI), revascularization, or >60% coronary artery stenosis prompting new medical treatment, adjudicated by three blinded reviewers. Published diagnostic thresholds were used to calculate diagnostic indices for each marker and for the multimarker panel.
Results: The prevalence of ACS was 7 in 414 (1.7%; 95% CI = 0.7% to 3.5%). Only MCP demonstrated a negative likelihood ratio [LR(-)] of less than 0.5, with a sensitivity of 85% (95% CI = 42% to 99%), specificity of 72% (95% CI = 67% to 76%), and LR(-) of 0.20 (95% CI = 0.04 to 0.71). For MPO, CRP, and BNP, LR(-) was 0.89 (95% CI = 0.26 to 2.05), 0.79 (95% CI = 0.40 to 1.01), and 0.90 (95% CI = 0.51 to 1.03), respectively. The sensitivity, specificity, and LR(-) of an abnormal multimarker panel were 86% (95% CI = 42% to 100%), 17% (95% CI = 13% to 21%), and 0.84 (95% CI = 0.15 to 3.12), respectively.
Conclusions: The prevalence of ACS was very low but was similar to reports from other CPUs. BNP and CRP had high specificities, but had limited sensitivities, whereas MPO had a low specificity. Only MCP had a low LR(-) and should be studied further. The combined multimarker panel had an unexpectedly low sensitivity and specificity, yielding an LR(-) of 0.84, suggesting that the panel would not be an efficient screening test to decrease unnecessary CPU testing.