MMP9 and myocardial infarction: Additionally, plasma MMP9 levels are correlated with LV dysfunction post-MI.14 Conversely, knockout (KO) of Mmp9 or selective MMP inhibition can decrease MI-induced cardiac rupture and LV dilation in mice.15,16 Moreover, overexpression of tissue inhibitor of metalloproteinase 1 (Timp1) preserves cardiac function in MI rats;17 whereas, Timp1 KO exacerbates LV remodeling post-MI.18 Thus, modulation of the macrophage function to reduce MMP expression or activation may decrease the risk of post-MI cardiac injury.