The Predictive Value Of The Renal Resistive Index For Contrast-induced Nephropathy In Patients With Acute Coronary Syndrome

Background:To find the influence factors of renal artery resistance index(RRI)in patients with acute coronary syndrome(ACS).Percutaneous coronary intervention(PCI)has been associated with contrast-induced nephropathy(CIN)at a rate that varies depending on the patient’s risk factors.This study was conducted to evaluate the predictive value of the RRI for CIN in patients with ACS undergoing PCI.Furthermore,we develop and validate a new risk prediction model for CIN based on RRI.MethodsSection1:This study enrolled consecutive patients with ACS undergoing PCI between October 2015 and March 2017.Renal Doppler ultrasound examinations to measure RRI were performed pre-PCI and at 1 h and 24 h after PCI.The primary endpoint was CIN,defined as a relative(≥25%)or absolute(≥0.5 mg/dL;44 μmol/L)increase in serum creatinine from baseline within 48 h after contrast exposure.Compared the differences of baseline data in patients between the high RRI group(>0.70)and the low RRI group(≤0.70).Multivariate logistic regression was performed using a forward stepwise selection process to further clarify the influence factors of RRI.Variables for inclusion were carefully chosen,including those that were considered clinically relevant or those that showed a significant outcome(p<0.15)in the univariate model.Section2:Baseline data were compared between CIN and non-CIN groups,and receiver operator characteristic(ROC)curve was used to analyze and compare the effectiveness of different times of RRI in prediction of CIN.Multivariate logistic regression was performed using a forward stepwise selection process to evaluate the independent values of RRI as categorical variables(based on the cutoff value)for CIN.Variables for inclusion were carefully chosen,including those that were considered clinically relevant or those that showed a significant outcome(p<0.15)in the univariate model.Developed risk prediction model for CIN based on the results of multivariate Logistic regression analysis.we assessed the goodness of fit and prognostic accuracy of the risk model according to the area under the ROC curve(AUC)and Hosmer-lemeshow test.Divided the patients into two groups based on the optimal cutoff point and compared the baseline data and long-term survival between the two groups.ResultsSection1:A total of 165 patients with ACS accepted emergency PCI were included,with an average value of RRI 0.67± 0.5,RRI>0.70 was found in 48 patients(29.1%).CIN was identified in 35 patients(21.2%);however,none of the patients required haemodialysis.Compared to the low RRI group,patients in the high RRI group were characterized by older,a higher proportion of patients with diabetes or chronic kidney disease(CKD),poorer basic renal function,and a higher incidence of CIN.Multivariate logistic regression analysis showed that RRI value was positively correlated with SCr,age and diabetes.Section2:Compared to patients without CIN,patients with CIN were characterized by older,higher incidence of hyperuricemia or CKD,poorer basic renal function and a higher incidence of MACE.Moreover,LAD as the target vessel was more likely observed in patients with CIN.ROC curve analysis showed that RRI 1h was the best predictor of CIN(area under the curve(AUC)=0.714,the optimal cutoff value was 0.706,with 74.3%sensitivity and 64.6%specificity).Multivariate logistic regression analysis showed that RRI1h>0.706,age≥65years and CKD were independent risk factors for CIN,while left ventricular ejection fraction(LVEF)was independent protective factor.According to the results of multivariate logistic regression analysis at the level of =0.05 by the conditional forward stepwise regression method,the CIN prediction formula was obtained:CIN Index =1.134x(CKD)+1.284x(RRI1h>0.706)+0.944 x(age≥65years)-0.06x(LVEF),AUC of the risk model was 0.784,with a sensitivity of 77.1%and a specificity of 69.2%.Hosmer-lemeshow goodness of fit test indicated that this risk model had a good degree of calibration(x2=7.159,p=0.52).Conclusions:(a)The baseline RRI value in patients with ACS was positively correlated with SCr,age and diabetes;(b)RRI1h>0.706,age≥65years and CKD were the independent risk factors for CIN in patients with ACS underwent emergency PCI,while LVEF was the protective factor;(c)The CIN risk model was constructed based on RRI1h>0.706,age≥65 years,CKD and LVEF,had a good discrimination and predictive ability.RRI appeared to be a novel risk factor of CIN.