Early indicators of coronary plaque instability also include pregnancy-associated plasma protein A (PAPP-A), a metalloproteinase exhibiting pro-atherosclerotic effects, and myeloperoxidase (MPO), an oxidative leukocyte enzyme, which has been shown to predict CE even in patients who are negative for troponin T [18], [19]. This evidence concerns the gene PAPPA and cholesteryl ester measurement.