Neutrophil activation precedes myocardial injury in patients with acute myocardial infarction

Ethyl pyruvate has anti-inflammatory and delayed myocardial protective effects after regional ischemia/reperfusion injury

PURPOSE

Ethyl pyruvate has anti-inflammatory properties and protects organs from ischemia/reperfusion (I/R)-induced tissue injury. The aim of this study was to determine whether ethyl pyruvate decreases the inflammatory response after regional I/R injury and whether ethyl pyruvate protects against delayed regional I/R injury in an in vivo rat heart model after a 24 hours reperfusion.

MATERIALS AND METHODS

Rats were randomized to receive lactated Ringer's solution or ethyl pyruvate dissolved in Ringer's solution, which was given by intraperitoneal injection 1 hour prior to ischemia. Rats were subjected to 30 min of ischemia followed by reperfusion of the left coronary artery territory. After a 2 hours reperfusion, nuclear factor κB, myocardial myeloperoxidase activity, and inflammatory cytokine levels were determined. After the 24 hours reperfusion, the hemodynamic function and myocardial infarct size were evaluated.

RESULTS

At 2 hours after I/R injury, ethyl pyruvate attenuated I/R-induced nuclear factor κB translocation and reduced myeloperoxidase activity in myocardium. The plasma circulating levels of inflammatory cytokines decreased significantly in the ethyl pyruvate-treated group. At 24 hours after I/R injury, ethyl pyruvate significantly improved cardiac function and reduced infarct size after regional I/R injury.

CONCLUSION

Ethyl pyruvate has the ability to inhibit neutrophil activation, inflammatory cytokine release, and nuclear factor κB translocation. Ethyl pyruvate is associated with a delayed myocardial protective effect after regional I/R injury in an in vivo rat heart model.

Lack of association between plasma myeloperoxidase levels and angiographic severity of coronary artery disease in patients with acute coronary syndrome

OBJECTIVE

To evaluate the association between plasma myeloperoxidase (MPO) levels and angiographic severity of coronary atherosclerotic lesions in patients with non-ST elevation acute coronary syndrome (ACS).

DESIGN AND METHODS

This cross-sectional study examined high-risk ACS patients who underwent coronary angiography within 72 h of the onset of symptoms by measuring their plasma MPO levels after sheath insertion. Gensini score was used to evaluate angiographic severity of coronary artery disease.

RESULTS

A total of 48 patients were included in the study. Median MPO levels and Gensini scores were 6.9 ng/mL (4.4-73.5 ng/mL) and 10 (0-87.5), respectively. Spearman's correlation coefficient did not show a significant association between MPO levels and Gensini scores (r (s) = 0.2; p = 0.177). There was no correlation between MPO and age, hypertension, diabetes, leukocyte count, troponin I, CK-MB ≥ 2 × ULN (upper limit of normal), TIMI risk score ≥ 4 and Gensini score in the multivariate analysis.

CONCLUSION

Our findings indicate that MPO expression is not associated with anatomical severity of coronary lesions in ACS.

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

BACKGROUND

Besides 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.

METHODS

MPO plasma levels were determined in 274 consecutive chest pain patients admitted to the emergency room.

RESULTS

A 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.

DISCUSSION

The 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.

Factors influencing local and systemic levels of plasma myeloperoxidase in ST-segment elevation acute myocardial infarction

Myeloperoxidase (MPO) is associated with risk in acute coronary syndromes. However, the precise role it plays in ST-elevation myocardial infarction (STEMI) remains unclear. In this study we tested the hypothesis that levels of MPO in plasma after a myocardial infarction are affected by its ability to bind to the endothelium and there is local release of the enzyme at the culprit lesion. We measured plasma MPO in systemic circulation and throughout the coronary circulation in patients with STEMI undergoing primary percutaneous coronary intervention (PCI). MPO levels at the femoral artery were higher (p <0.001) in patients with STEMI (n = 67, median 45 ng/ml, interquartile range 34 to 83) compared to control patients (n = 12, 25 ng/ml, 19 to 30) with chronic stable angina undergoing elective PCI. After administration of the anticoagulant bivalirudin in 13 patients with STEMI, plasma MPO was increased only at the culprit coronary artery lesion before PCI (178 ng/ml, 91 to 245) versus all other sites (femoral artery 86 ng/ml, 54 to 139, p = 0.019). Administration of heparin caused a marked increase of plasma MPO. Even so, it was still possible to detect an increase of plasma MPO at culprit lesion in patients with STEMI (n = 54, 171 ng/ml, 122 to 230) versus controls (n = 12, 136 ng/ml, 109 to 151, p <0.05) after heparin and before PCI. MPO levels were higher at the culprit lesion in patients with STEMI who presented early and in those with restricted flow (p <0.05). In conclusion, our results demonstrate that, in addition to a systemic increase of MPO in patients presenting early with STEMI, levels of this leukocyte enzyme are increased at the culprit coronary lesion before PCI.