| Background and objectiveCoronary heart disease (CHD) seriously threatens human health. Acute coronary syndrome (ACS) covers30to40percents of CHD, including unstable angina pectoris(UAP), ST-elevation myocardial infarction (STEMI) and non ST-elevation myocardial infarction (NSTEMI). The incidence is increasing year by year. The main treatment strategy for patients with ACS is anti-coagulation, anti-platelet and revascularization as early as possible. Except thrombolytic therapy, percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) were also important revascularization treatments. PCI is effective to open the occluded artery, minimally-invasive and simple with fast recovery after the procedure. In recent years PCI has become more and more recognized, and could significantly reduce serious complication and death. However, the ratio of restenosis was still5%-9%for drug-eluting stents. Seeking for an ideal index to evaluate the risk stratification and prognosis in patients with ACS is a key problem for clinical doctors. Many studies have reported cystatin C(CysC) participated in the occurrence and development of CHD and emergered as an effective predictor for the patients with ACS. CysC was one member of cysteine protease inhibitors superfamily, and a new marker of glomerular filtration rate (GFR). It played an important role in maintaining the balance between the dissolved and anti-dissolved acitivity in the artery wall protein, regulating the cell matrix degradation and influencing atherosclerosis and myocardial remodeling. Otherwise CysC was related with the vulnerable plaques and inflammation. The risk of death, nonfatal myocardial infarction and heart failure with higher CysC inceased1.9-9.6times compared with lower, and the threshold value ranged0.93-1.3mg/L. However, few studies showed its correlation with prognosis of patients with ACS after PCI. This study was to evaluate the value and threshold of CysC in assessing the of the prognosis of patients with ACS.MethodA total of660patients, who were diagnosed ACS and underwent PCI successfully from January2009to June2010in Cardiovascular Dept, the first affiliated hospital of zhengzhou university, were enrolled. CysC and other basic laboratory examination data were recorded in24hours after adimission. Besides other clinical results were obtained. All patients were followed up by telephone or outpatients interview from March to July in2011, and the end-points were recorded. The factors were studied which possibly related with CysC. The patients were divided into four groups according to CysC level: Q1(CysC<1.02mg/L), Q2(1.02mg/L<CysC<1.17mg/L), Q3(1.17mg/L<CysC<1.35mg/L) and Q4(CysC>1.35mg/L). Multivariate step-wise logistic regression and the receiver-operating-characteristic(ROC) curve were employed to evaluate the risk factors for the patients with ACS. The cumulative survival rates and the correlated risk fators were analyzed in Kapan-Meier survival curves and cox risk proportion regression model.Results1. The median of CysC in patients with UAP, STEMI and NSTEMI were1.21±0.31mg/L,1.22±0.38mg/L and1.25±0.24mg/L. Analysis of variance between three group showed no difference (F=3.275, P=0.11).2. The rank correlation analysis showed the CysC level were positively corrected with blood creatinine(r=0.568,P<0.001), uric acid(r=0.284,.P<0.005) and negatively corrected with GFR(r=-0.356, P<0.005).3. A total of606(91.7%) patients successfully accepted follow-up. Mean follow-up time were14.3±1.7months.95patients(15.7%) experienced end points. The median of CysC in patients with and without end points were1.37±0.43mg/L and1.21±0.39mg/L, respectively. The difference was statistically significant(t=-3.612, P<0.05). Univariate analysis indicated that age (r=0.094, P=0.021), creatinine (r=0.098, P=0.016), CysC(r=0.184, P<0.005), GFR (r=-0.137, P=0.001), LVEF (r=-0.105, P=0.039) were risk factors of poor prognosis.4. Multivariate step-wise logistic regression demonstrated that the plams CysC were an independent predictor of poor prognosis in patients ACS after PCI. Compared with group Q1, the hazard ratio in group Q3and group Q4patients was separately3.653(95%CI1.148-11.622, P=0.028) and7.74(95%CI2.489-24.083, P<0.005). The area under the curve of the ROC of CysC in predicting adverse cardiovascular events in patients with ACS was0.646(95%CI0.586-0.706), P<0.001.The CysC cut-off value of1.17mg/L had a sensitivity of69.5percent, a specificity of56.3percent for predicting end points.5. Kaplan-Meier survival curve showed that the cumulative survival rate in group Q2, Q3and Q4was lower than in group Ql. Log-rank test indicated that the difference was statistically significant (P<0.05). Cox proportional hazard model showed CysC remained as an independent predictor of adverse cardiovascular events. The risk ratio of Q3and Q4group was3.930(95%CI:1.306-11.829, P=0.015) and6.380(95%CI:2.171-18.751, P=0.001), respectively.ConclusionThe serum CysC could provide important clinical value for predicting clinical severity and prognosis for ACS patients after PCI. Serum level of CysC above1.17mg/L in patients with ACS after PCI indicate a poor prognosis. To improve the prognosis, clinical doctors should pay great attention to the patients condition, and deal with the patients aggressively. |
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