Lack of Diagnostic and Prognostic Utility of Circulating Plasma Myeloperoxidase Concentrations in Patients Presenting with Dyspnea

BACKGROUND: Plasma myeloperoxidase (MPO), an inflammatory biomarker, is associated with increased mortality in patients with acute coronary syndrome or chronic left ventricular systolic dysfunction. We sought to assess the diagnostic accuracy of MPO for acute decompensated heart failure (ADHF) and its prognostic value for patients with acute dyspnea. METHODS: In a prospective, observational study conducted in 5 US centers, 412 patients [mean (SD) age, 58 (14) years; 39% women] presenting with dyspnea to the emergency department were enrolled and followed for 1 year. Clinical, serum/plasma biomarker [MPO, B-type natriuretic peptide (BNP), N-terminal proBNP (NT-proBNP)], and transthoracic echocardiographic data were obtained. RESULTS: We observed no differences in MPO concentration (P = 0.07) between patients with ADHF [n = 147; median, 553 pmol/L; interquartile range (IQR), 415-738 pmol/L] and those without ADHF (n = 265; median, 576 pmol/L; IQR, 413-884 pmol/L. The diagnostic accuracy for ADHF was excellent for BNP (area under the ROC curve (AUC), 0.90; P < 0.001] and NT-proBNP (AUC, 0.90; P < 0.001) but poor for MPO (AUC, 0.46; P = 0.18). MPO appeared uncorrelated with echocardiographic measures of cardiac structure or function. The observed 1-year mortality rate was 12%. MPO concentration also appeared unrelated to mortality [hazard ratio, 1.25 (above vs below the median); 95% CI, 0.71-2.18], whereas BNP (P = 0.001) and NT-proBNP (P < 0.001) were significant predictors of mortality. MPO concentration provided no prognostic information in addition to that of BNP or NT-proBNP concentration. CONCLUSIONS: Unlike natriuretic peptides, MPO concentration was not predictive of ADHF diagnosis or 1-year mortality in a heterogeneous sample of emergency department patients with acute dyspnea. (C) 2008 American Association for Clinical Chemistry