Prognostic value of myeloperoxidase in patients with chest pain

BACKGROUND: Inflammation is linked to adverse outcomes in acute coronary syndromes. Myeloperoxidase, an abundant leukocyte enzyme, is elevated in culprit lesions that have fissured or ruptured in patients with sudden death from cardiac causes. Numerous lines of evidence suggest mechanistic links between myeloperoxidase and both inflammation and cardiovascular disease. METHODS: We assessed the value of plasma levels of myeloperoxidase as a predictor of the risk of cardiovascular events in 604 sequential patients presenting to the emergency department with chest pain. RESULTS: Initial plasma myeloperoxidase levels predicted the risk of myocardial infarction, even in patients who are negative for troponin T (<0.1 ng per milliliter) at base line (P<0.001). Myeloperoxidase levels at presentation also predicted the risk of major adverse cardiac events (myocardial infarction, the need for revascularization, or death) within 30 days and 6 months after presentation (P<0.001). In patients without evidence of myocardial necrosis (defined as those who were negative for troponin T), the base-line myeloperoxidase levels independently predicted the risk of major adverse coronary events at 30 days (unadjusted 2nd, 3rd, and 4th quartile odds ratios, 2.2 [95 percent confidence interval, 1.1 to 4.6], 4.2 [95 percent confidence interval, 2.1 to 8.4], and 4.1 [95 percent confidence interval, 2.0 to 8.4], respectively) and at 6 months. CONCLUSIONS: A single initial measurement of plasma myeloperoxidase independently predicts the early risk of myocardial infarction, as well as the risk of major adverse cardiac events in the ensuing 30-day and 6-month periods. Myeloperoxidase levels, in contrast to troponin T, creatine kinase MB isoform, and C-reactive protein levels, identified patients at risk for cardiac events in the absence of myocardial necrosis, highlighting its potential usefulness for risk stratification among patients who present with chest pain.