Lipoprotein-Associated Phospholipase A2 in Cardiac Disease: a Potential Early Biomarker of Unstable Coronary Artery Disease

Background Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a serine lipase that deteriorates the stability of atherosclerotic plaques. This study aims to investigate Lp-PLA2 activity and its diagnostic potential in the early period of acute coronary syndromes (ACS). Methods Two hundred sixty-two patients referred for acute chest pain within 6 hours of symptom onset were included. Among the candidates, 67 were diagnosed with ST-elevation myocardial infarction (STEMI) and 167 unstable angina (UA). The STEMI patients were divided into cardiac troponin I (cTnI) negative and cTnI positive groups according to the cTnI values at admission. As control, 184 stable coronary artery disease (CAD) patients were also enrolled. Blood samples were collected immediately after admission. The levels of Lp-PLA2 activity and lipids were measured. The diagnostic value of Lp-PLA2 was determined based on receiver operating characteristic curves. Results Lp-PLA2 activity levels of STEMI and UA groups were dramatically higher than that in CAD group. However, Lp-PLA2 values showed no marked difference between STEMI and UA groups. Similar results were obtained between cTnI negative and positive groups among STEMI patients. In the three groups combined, there was a significant correlation between LDL-C concentration and Lp-PLA2 activity. In the ACS group, the area under the curve was 0.719 (95% CI: 0.671 - 0.768), and the optimal Lp-PLA2 cutoff value was 306.4 U/L, with a sensitivity of 67% and specificity of 69%. Conclusions Lp-PLA2 activity was significantly elevated in the early stage of ACS. The obtained statistical data suggest that Lp-PLA2 activity may represent a novel early marker of unstable coronary disease.