Changes Of Serum Cystatin C In Patients With Acute Myocardial Infarction

Background: Overexpression of elastolytic cysteine and aspartic proteases, known as cathepsins, is implicated in atherogenesis. Imbalance of proteolytic and antiproteolytic levels plays a important role in vascular wall remodeling and the stability of the atherosclerosis plaque. Cystatin C is the most abundant protease inhibitor in the plasma. Low plasma levels have been found in patients' with aortic aneurysms and they seem correlated with the extension of the aortic lesions in early aneurysms detected by ultrasonography. Low intralesion Cystatin C expression have also been found in patients with established aortic aneurysm and atherosclerosis.Objective: To explore the changes of serum Cystatin C and its value as a sign of early diagnosis and predicting stability of atherosclerotic plaque in patients with acute myocardial infarction.Methods: In this study, serum levels of Cystatin C have been investigated in patients with acute myocardial infarction, unstable angina and controls.Results: Cystatin C was lower in acute myocardial infarction (AMI) patients during onset but the difference did not reach statistical significance compared to controls(P=0.28). Nevertheless, when Cystatin C/Creatinine ratio was considered, significantly lower values were found in acute AMI patients(P=0.003). Cystatin C plasma levels increased in the same AMI patients in a week after the acute event(P=0.04). At univariate analyses, Cystatin C levels were positively correlated with age and creatinine. The same variables were also independently correlated with Cystatin C levels in a multiple-regression analysis with a multiple R=0.413.