MPO and coronary artery disorder: More particularly, MPO is a heme-group enzyme in azurophilic granules of neutrophiles and monocytes and works as a peroxidase, which triggers oxidative stress in inflammatory pathways, while MMP-9 is a zinc containing endopeptidase, essential in cardiac and vascular remodeling by degrading the extracellular matrix; increased circulating levels of both MPO and MMP-9 are associated with worse prognosis in patients with coronary artery disease [120].