Risk Prediction with Serial Myeloperoxidase Monitoring in Patients with Acute Chest Pain

BACKGROUND: Although myeloperoxidase (MPO) monitoring is predictive for cardiovascular outcomes in suspected acute coronary syndromes, the value of serial testing is unknown.

METHODS: We investigated the relationship between serial MPO concentrations in 490 individuals with acute chest pain and incident major adverse cardiac events (MACE) during 6 months of follow-up. We measured MPO with the CardioMPO assay, and cardiac troponin I (cTnI), with the Abbott Architect assay.

RESULTS: Plasma MPO concentrations during the first 16 h were higher in individuals who experienced MACE. Higher MPO quartiles predicted a greater likelihood of 6-month MACE at baseline [OR (95%CI), 2.4 (1.4–4.1), P = 0.001 for highest vs lowest quartile] and all subsequent time points, with strongest predictive ability found in 16-h postbaseline samples [9.9 (4.7–20.9), P < 0.001 for highest vs lowest quartile]. MPO was predictive for MACE among individuals whose cTnI remained normal (<0.028 µg/L). The lowest rate of missed cases was found when MPO was <640 pmol/L at baseline and all other time points. Serial MPO monitoring predicted MACE risk better than baseline MPO measurements alone (c statistic 0.813 vs 0.602; P = 0.002), including in individuals whose cTnI remained normal (c statistic 0.903; P = 0.009). Combined serial cTnI and MPO testing improved accuracy for predicting 6-month MACE, reduced the number of missed MACE events from cTnI testing alone, and improved risk classification in 26.1% of patients.

CONCLUSIONS: MPO concentrations are predictive of outcome up to 16 h after presentation with chest pain and predict events missed by cTnI testing, supporting a potential role in rapid patient triage.

Stephen J. Nicholls1,2,3,*, W.H. Wilson Tang1,2,3, Danielle Brennan1, Marie-Luise Brennan1,2,3, Shirley Mann2,3, Steven E. Nissen1 and Stanley L. Hazen1,2,3

1 Department of Cardiovascular Medicine, and
2 Department of Cell Biology, and
3 Center for Cardiovascular Diagnostics and Prevention, Cleveland Clinic, Cleveland, OH