Myeloperoxidase aids prognostication together with N-terminal pro-B-type natriuretic peptide in high-risk patients with acute ST elevation myocardial infarction

Background: Inflammation plays a critical role in acute myocardial infarction (MI). One such inflammatory marker is myeloperoxidase (MPO). Its role as a predictor of death or MI in patients with ST segment elevation myocardial infarction (STEMI) is unclear. Aim: To investigate the role of MPO as a predictor of death or MI in patients with STEMI and to compare it with N-terminal pro-B-type natriuretic peptide (NT-BNP). Method: 384 post STEMI patients were studied. Patients were followed up for the combined end point of death or readmission with non-fatal MI. Results: There were 40 deaths and 37 readmissions with MI. Median MPO was raised in patients experiencing death or MI than in survivors (median (range), 50.6 (15.3-124.1) ng/ml vs 33.5 (6.6-400.2) ng/ml, p = 0.001). Using a Cox proportional hazards model, log median MPO (HR 6.91, 95% CI 1.79 to 26.73, p = 0.005) and log median NT-BNP (HR 4.21, 95% CI 1.53 to 11.58, p = 0.005) independently predicted death or non-fatal MI. MPO had predictive power in both below and above median NT-BNP levels (log rank 5.60, p = 0.020 and log rank 5.12, p = 0.024, respectively). The receiver-operating curve for median NT-BNP yielded an area under the curve (AUC) of 0.72 (95% CI 0.65 to 0.79, p<0.001); for median MPO, the AUC was 0.62 (95% CI 0.55 to 0.69, p = 0.001). The logistic model combining the two markers yielded an AUC of 0.76 (95% CI 0.69 to 0.82, p<0.001). Conclusion: MPO and NT-BNP may be useful tools for risk stratification of all acute coronary syndromes, including patients with STEMI at higher risk.