Usefulness of plasma matrix metalloproteinase-9 level in predicting future coronary revascularization in patients after acute myocardial infarction

OBJECTIVES: This study aims to determine whether plasma levels of matrix metalloproteinases (MMPs) and inflammatory markers can predict the long-term prognosis of coronary revascularization in patients after acute myocardial infarction (AMI). BACKGROUND: MMPs have been implicated in the development of atherosclerosis and plaque rupture in acute coronary syndrome. METHODS: Ninety-six consecutive patients (63±11 years) diagnosed with myocardial infarction were enrolled. All patients were followed up for 43±12 months. Plasma levels of MMP-2 and MMP-9 were determined from blood samples collected immediately after hospitalization. Coronary revascularization was defined as having received a percutaneous coronary intervention or a coronary artery bypass graft surgery. RESULTS: A total of 29 patients (30%) had undergone coronary revascularization during the follow-up period, including 27 percutaneous coronary intervention and two coronary artery bypass graft surgery. The baseline characteristics were similar between groups with or without revascularization. Patients with coronary revascularization had significantly higher MMP-9 levels (P=0.048), but not MMP-2 levels. In addition, a positive correlation was found between circulating MMP-9 level and total cholesterol (r=0.250, P=0.016) and low-density lipoprotein-cholesterol (r=0.284, P=0.009). All patients were divided into a high-MMP-9 group (highest tertile?1.10 ng/ml) and a low-MMP-9 group (<1.10 ng/ml). The incidence of coronary revascularization was significantly increased in the high-MMP-9 group (P=0.034). In a multivariate Cox regression analysis that included MMP-9 and classical risk factors, the MMP-9 level was an independent predictor of coronary revascularization in patients after AMI (hazard ratio, 2.72; 95% confidence interval, 1.24-5.98; P=0.026). CONCLUSION: Increased plasma levels of MMP-9 but not MMP-2 or inflammatory markers predict future coronary revascularization, and a significant association was observed with MMP-9 and low-density lipoprotein-cholesterol. These findings suggest a pivotal role of MMP-9 in atherothrombosis in AMI patients.