The Predictive Value Of Combining Microalbuminuria And Serum Cystatin C For The Presence Of Unstable Angina

Background and Objective: Coronary atherosclerotic heart disease (CHD)consists of acute coronary syndrome and chronic coronary artery disease. Unstableangina pectoris is also a major type of acute coronary syndrome. In recent years,microalbuminuria and serum cystatin C have been detected as sensitive indicators ofimpaired renal filtration. A number of studies on the association betweenmicroalbuminuria, serum cystatin C and CHD have been conducted. The relationshipbetween microalbuminuria and other risk factors of CHD has been demonstrated.Microalbuminuria, an independent risk factor for cardiovascular disease, can predictthe development of atherosclerosis-related ischemic cardiovascular events.Meanwhile, some studies have confirmed the association between high levels ofserum cystatin C and severe coronary artery disease. In recent years, their significantroles in the diagnosis and treatment of CHD have been gradually noticed. However,MA is unstable and always influenced by position, movement, blood pressure and other factors.Serum cystatin C only varies with the changes of glomerular filtration rate. The predictive valueof combining MA and serum cystatin C for UA is still controversial currently. This study wasdesigned to analysis the levels of MA and serum cystatin C in patients with UA diagnosed bycoronary angiography, and investigate the predictive value of combining both factors for thepresence of UA.Subjects and Methods:133consecutive inpatients diagnosed of unstableangina by coronary angiography from January2013to September2013in thecardiac care unit of the First Affiliated Hospital of Dalian Medical University, were selected. Among them,90males and43females, aged between30and94years(mean age64.7±12.3years) were included.57patients had single-vessel CHD,40had two-vessel CHD and36had three-vessel CHD (including lesions in left mainartery). Meanwhile, another68patients, including32males and36females, agedbetween38and62years (mean age49.5±8.4years), free of CHD according tocoronary angiography were recruited into the control group.Venous blood samples were taken from all the subjects were after12hours offasting to detect high-sensitivity CRP, serum Cystatin C and serum creatinine, urea,glucose, lipids and other routine biochemical markers within48hours afteradmission into hospital. Urine specimen was sampled in the morning to measuremicroalbuminuria. Left ventricular diameter and left ventricular ejection fractionwere measured with color Doppler ultrasound by two experienced physicians.Results:1. Serum Cystatin C and microalbuminuria in patients with unstable angina wassignificantly higher than those in the control group (P <0.05).2. Multivariate logistic regression showed gender, total cholesterol,high-sensitivity CRP, serum cystatin C, and microalbuminuria are independent riskfactors for unstable angina. High density lipoprotein was a protective factor ofunstable angina.3. The results of Pearson linear correlation showed that microalbuminuria andserum cystatin C levels were positively correlated (r=0.763, P=0.016).4. Pearson linear correlation showed that microalbuminuria and serumcreatinine were positively correlated (r=0.635, P=0.038). In addition, serumcystatin C and serum creatinine were positively correlated (r=0.584, P=0.042).5. Patients with three-vessel disease had significantly higher serum cystatin Clevels (1.209mg/L) than those with two-vessel lesions (1.114mg/L) and those withsingle-vessel disease (1.033mg/L). Patients with two-vessel disease had higherserum cystatin C levels than those with single-vessel disease. The differences werestatistically significant (P <0.05).6. Patients with three-vessel disease had significantly higher microalbuminuria levels (1.26mg/dl) than those with two-vessel lesions (1.12mg/dl) and those withsingle-vessel disease (0.93mg/dl). Patients with two-vessel disease had highermicroalbuminuria levels than those with single-vessel disease. The differences werestatistically significant (P <0.05).7. The predictive value of microalbuminuria and serum cystatin C for unstableanginaThe ROC curves showed that microalbuminuria and serum cystatin C werepredictive of unstable angina. Serum cystatin C was more valuable thanmicroalbuminuria (area under curve0.933vs.0.783)(P <0.05).8. The predictive value of microalbuminuria and serum cystatin C incombination for unstable anginaROC analysis showed the area under curve was0.938with regard to thecombination of microalbuminuria and serum cystatin C (P<0.05), indicating thecombination was more accurate to predict unstable angina. Moreover, thecombination was more valuable when compared to microalbuminuria (area undercurve=0.783).Conclusion:1. Microalbuminuria and serum cystatin C were positivelycorrelated in patients with unstable angina.2. Microalbuminuria and serum cystatin C increase with the severity ofcoronary artery lesions.3. The combination of microalbuminuria and serum cystatin C can be used as areliable predictor of the severity of coronary artery lesions in patients with unstableangina.