Diagnostic value of MPO plasma levels in patients admitted for suspected myocardial infarction

BackgroundBesides its well-established role in atherosclerosis, myeloperoxidase (MPO) has gained attention as a prognostic indicator in cardiovascular disease. Previous studies assessed MPO retrospectively and at a single time point. The current study aimed to evaluate the prognostic information of MPO prospectively and in consecutive measurements in patients presenting with chest pain.MethodsMPO plasma levels were determined in 274 consecutive chest pain patients admitted to the emergency room.ResultsA total of 100 patients (36.5%) were finally diagnosed for acute myocardial infarction (AMI). Patients with AMI had significantly higher MPO levels than patients without AMI. Importantly, MPO levels were elevated in patients finally diagnosed for AMI even when troponin I (TNI) was negative (cutoff: 0.032 ng/ml). Overall, MPO yielded a negative predictive value (NPV) of 85.5% (95% confidence interval (CI): 82.6–88.4) and a sensitivity for diagnosing AMI of 80.0% (95% CI: 75.8–84.2) compared to a NPV of 91.7% (95% CI: 89.5–94.0) and a sensitivity of 85.9% (95% CI: 82.3–89.5) for TNI. For patients with a symptom onset of ≤ 2 h the sensitivity of MPO increased to 95.8% (95% CI: 93.7–97.9) whereas the sensitivity of TNI dropped to 50.0% (95% CI: 44.8–55.2). The negative predictive value of MPO for this group of patients was 95.6% (95% CI: 94.0–97.3) compared to 73.3% (95% CI: 69.8–76.9) for TNI.DiscussionThe current data underscore the role of MPO as diagnostic marker in acute coronary disease; however the additive information derived from MPO is restricted to patients presenting in the early phase of symptom onset.