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Table of Contents
ORIGINAL ARTICLE
Year : 2019  |  Volume : 9  |  Issue : 2  |  Page : 88-94

Serum cystatin c and renal dysfunction in transradial versus transfemoral approaches in primary percutaneous coronary intervention


Department of Cardiology, Faculty of Medicine, Zagazig University, Zagazig, Egypt

Date of Web Publication23-Sep-2019

Correspondence Address:
Dr. Wael Ali Khalil
Department of Cardiology, Faculty of Medicine, Zagazig University, Zagazig
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/JICC.JICC_4_18

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  Abstract 


Objectives: Contrast-induced nephropathy is one of the most common adverse side effects in ST-segment elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PCI). Serum cystatin C level is a biomarker of the renal function test. We aimed to compare the degree of renal dysfunction in transradial primary PCI versus transfemoral primary PCI and to use of serum cystatin C as a predictor of contrast-induced nephropathy. Methods: This study included 90 patients who were admitted to the hospital with STEMI and who underwent a primary PCI and they were divided into Group I (45 patients): a primary PCI via femoral approach and Group II (45 patients): a primary PCI via radial approach. We estimated both serum cystatin C and serum creatinine after 72 h of primary PCI. Results: Serum cystatin C level post-PCI had high sensitivity results in correlation with CIN and non-CIN groups. Further, the significant effects were found in all patients in association with serum cystatin C before and after PCI. The cutoff value of serum cystatin C with receiver operating characteristic curve analysis before PCI was 1.1 mg/dL and after PCI was 1.3 mg/dL. Conclusion: The transradial approach for a primary PCI is an effective and safe approach alternative to the femoral approach. Serum cystatin C is a biomarker and a predictor of the occurrence of contrast-induced nephropathy in STEMI patients who underwent a primary PCI and is one of the most sensitive renal markers regarding CIN in comparison to serum creatinine level.

Keywords: Contrast-induced nephropathy, serum cystatin-C, transradial and transfemoral primary percutaneous coronary intervention


How to cite this article:
Khalil WA, Abdelhameed MG, Elmenshawy MD, Elhelaly A. Serum cystatin c and renal dysfunction in transradial versus transfemoral approaches in primary percutaneous coronary intervention. J Indian coll cardiol 2019;9:88-94

How to cite this URL:
Khalil WA, Abdelhameed MG, Elmenshawy MD, Elhelaly A. Serum cystatin c and renal dysfunction in transradial versus transfemoral approaches in primary percutaneous coronary intervention. J Indian coll cardiol [serial online] 2019 [cited 2019 Dec 7];9:88-94. Available from: http://www.joicc.org/text.asp?2019/9/2/88/267495




  Introduction Top


Contrast-induced nephropathy (CIN) is an increase of serum creatinine >0.5 mg/dL or >25% increase of basal serum creatinine level after administration of contrast media within 48–72 h.[1] CIN is the most common side effects in ST-segment elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PCI) which were higher compared with patients undergoing elective PCI.[2] Many studies showed the advantages of the transradial approach over the transfemoral approach.[3] Serum cystatin C level is a biomarker of renal function test like serum creatinine level for the detection of renal impairment as estimated by glomerular filtration rate.[4] The aim of this study was to compare the degree of renal dysfunction by using serum cystatin C as a predictor of contrast-induced nephropathy in transradial versus transfemoral primary PCI.


  Methods Top


This study was conducted in the cardiology department which included 90 patients who were admitted to the hospital with STEMI/acute coronary syndrome and who underwent a primary PCI. Acute coronary syndrome (STEMI) patients were managed according to the European Society of Cardiology guidelines 2015.[5] Patients who have proper pulsating radial artery and adequate collateral connection with the ulnar artery as demonstrated by Allen's test and pulse oximetry were included in this study.[6] Patients who have undergone elective PCI, acute coronary syndrome (STEMI) out-of-time window of primary PCI, regular hemodialysis, and vascular status (absence of pulse in both femoral and radial arteries and abnormal Allen's test results) were excluded from the study. We have done all of the following for each patient: (1) full history was obtained including age, gender, smoking, diabetes mellitus, dyslipidemia, hypertension, family history of early ischemic heart disease, and previous PCI procedures; (2) the history of cerebrovascular stroke, renal impairment, and peripheral vascular disease; and. (3) a full clinical examination was done including vital signs, complete cardiac clinical examination to assess the Killip classification of the patient done. A 12-lead surface electrocardiogram was done for each patient on admission, after finishing the PCI which used for determining the degree of ST-segment resolution early after mechanical reperfusion.[7] All patients underwent a conventional transthoracic echocardiographic examination.[8] Each patient had the following investigations on admission: serum creatinine, cystatin C, electrolytes, complete blood count, random blood sugar, troponin, and creatine phosphokinase (CPK) (total CPK, and creatine kinase MB-fraction). In the coronary care unit, all patients had routine serial cardiac enzymes assay every 8 h for the 1st day after admission and then every 24 h till normalization.[9] Follow-up serum creatinine and serum cystatin C level after primary PCI within 72 h to diagnose (CIN) contrast -induced nephrotoxicity which was defined as impairment in renal functions (an increase in serum creatinine by >25% above the basal level or 0.5 mg/dl) occurring within 48–72 h after the intravascular administration of contrast dye in the absence of any other cause.[10] Coronary angiography and primary PCI (transradial and transfemoral approaches) including time of procedure and volume of contrast media were done.[11]

The study groups were divided into Group I (45 patients): a primary PCI through the femoral approach and Group II (45 patients): a primary PCI through the radial approach.

In Group I, transfemoral approach was made with femoral artery cannulation using the Seldinger technique.[12]

In Group II, transradial approach was made with radial artery cannulation using 19-gauge arterial needles 1 cm proximal from the styloid process at 45° from lateral to medial.[13]

Ethical consideration

The ethics committee approved this study. Written consent from every patient to participate in the study was obtained, and the study was consistency with ethical standards.

Statistical analysis

Statistical analysis was performed using the SPSS software version 20.0 for Windows (SPSS Inc., Chicago, IL, USA). Quantitative data were expressed as the mean ± standard deviation (SD) and median (range), and qualitative data were expressed as absolute frequencies “'number'” and relative frequencies (percentage). We used the Student's t-test to compare two groups of normally distributed data. We used the Mann–Whitney U-test to compare two groups of nonnormally distributed data. We used Wilcoxon signed-rank test to compare the two dependent groups. We used the Chi-square or Fisher's exact test. We also used the receiver operating characteristic (ROC) curve analysis to identify the optimal cutoff values of serum cystatin C with maximum sensitivity and specificity for prediction of CIN. Area under curve (AUC) was also calculated and criteria to qualify for AUC were as follows: 0.90–1 = excellent, 0.80–0.90 = good, 0.70–0.80 = fair; 0.60–0.70 = poor; and 0.50–0.6 = fail. The optimal cutoff point established at the point of maximum accuracy. All tests were two sides. P < 0.05: significant (S), P < 0.001: highly statistically significant (HS), and P > 0.05: nonstatistically significant (NS).


  Results Top


This study included 90 patients with acute myocardial infarction who underwent primary PCI by two approaches (45 radial and 45 femoral) with follow-up renal functions during the hospital stay by serum creatinine level and serum cystatin C level [Table 1]. This study population included 66 males and 24 females with the age (mean ± SD) (55.47 ± 10.12) and the weight (75.66 ± 8.73). In the femoral approach, the number of males was 30 (66.7%) patients and of females was 15 patients (33.3%). In the transradial approach, the males were 36 (80%) patients and the females were nine patients (20%). The most used method to males was the radial one. The least used approach to females was the radial as well. As regarding the demographic data, there was no statistically significant difference between the studied groups. According to the risk factors, there was no significant difference as regarding smoking, hypertension, and dyslipidemia but significant results concerning diabetes mellitus. Patients with diabetes were 62.2% of the femoral group and 35.6% of the radial group. Ten patients developed CIN of which only five of these patients had diabetes (four femoral approaches and one radial approach) [Table 2].
Table 1: Comparison between the studied groups as regarding changes in renal functions in femoral and radial approaches (before and after primary percutaneous coronary intervention)

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Table 2: Comparison between patients with contrast-induced nephropathy and without contrast-induced nephropathy

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As regards the routine renal function tests before PCI, the serum creatinine was higher in the radial group (1.18 ± 0.38 mg/dL) than in the femoral group (0.97 ± 0.17 mg/dL) and also the serum urea level was higher in the radial group. There were highly significant results regarding serum cystatin C level before and after PCI in each group [Table 3].
Table 3: Comparison between patients with contrast-induced nephropathy and without contrast-induced nephropathy

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As regards the efficacy of the two approaches (femoral vs. radial) on developing CIN, there was a significant differences between the two groups (P<0.044). Serum cystatin C level post-PCI had high sensitivity results in correlation with CIN and non-CIN groups. Further, the significant effects were found in all patients in association with serum cystatin C before and after PCI. The cutoff value of serum cystatin C with receiver operating characteristic curve analysis before PCI was 1.1 mg/dL and after PCI was 1.3 mg/dL [Table 4], [Table 5], [Table 6] and [Figure 1].
Table 4: Comparison between the studied groups as regarding changes in renal functions before and after primary percutaneous coronary intervention in patients with contrast-induced nephropathy and without contrast-induced nephropathy

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Table 5: Serum cystatin C (mg/L) as a biomarker for occurrence of contrast-induced nephropathy in ST-segment elevation myocardial infarction patients underwent primary percutaneous coronary intervention; receiver operating characteristic curve analysis

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Table 6: Comparison between the studied groups regarding contrast volume in femoral versus radial approach

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Figure 1: Receiver operating characteristic curve of serum cystatin C (mg/L) as a biomarker for the occurrence of contrast-induced nephropathy in ST-segment elevation myocardial infarction patients underwent percutaneous coronary intervention

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  Discussion Top


Coronary angioplasty and stenting was performed through the transfemoral approach in most Egyptian centers. In a primary PCI, the suspected complex intervention is higher than elective interventions, so the need for complex tools was higher and so the easier was through the femoral approach. In our study, we included 90 patients according to the difference between the efficacy of the two approaches on renal functions and developing contrast-induced nephropathy. Our statistical analysis showed significant results between the two approaches, and these are like what was described by Vuurmans et al. and Andreucci et al.[14],[15] There is a growing perception that, within these different intra-arterial procedures, there is a different risk factor for renal involvement when using radial or femoral access. The femoral access leads to the greatest risk because of its proximity to the high flow bed of the renal arteries.[14] Hypotension and cardiogenic shock are common complications associated with myocardial infarction which decreasing renal perfusion and increasing incidence of renal impairment. Complex lesions and difficult interventions need much more time and increase the amount of dye using which increases the incidence of renal impairment post a primary PCI. In this study, the demographic data and procedural characteristics as age, sex, hypertension, dyslipidemia, smoking, and weight were statistically nonsignificant, except for diabetes mellitus showing significant results between studied groups. The results of this study were similar to the results of Pancholy et al. where 283 consecutive patients underwent primary PCI, of which 177 by the transradial approach and 106 by transfemoral approach. In this study, the demographic data and procedural characteristics were statistically nonsignificant. The percutaneous transradial approach for PCI is an effective and safe approach alternative to the femoral approach due to favorable anatomical.[16] The results of this study were similar to the results of Yves et al. where 1224 cases were registered for a primary PCI at two European sites using either transradial access or transfemoral access and concluded that angioplasty was successful in 95% of both radial and femoral access patients. The time taken for arterial puncture and sheath insertion was longer in the radial group compared with the femoral group with highly significant results. The time of radial artery puncture until sheath insertion was 1.15 ± 0.42 min, and the time of femoral artery puncture until sheath insertion was 3.15 ± 1.38 min.[17] These results were against the results of Louvard et al. and Hammon et al. where the overall procedural time, procedural outcome, and the rate of TIMI3 flow (88%–91%) did not differ between the transradial and transfemoral approach[18],[19] In this study, no patient shifted from radial approach to femoral approach, but two patients shifted from femoral to radial approach; the first was because highly aortic tortuosity and the second was due to the old stable abdominal aortic aneurysm. In this study, the contrast-induced nephropathy group compared to the noncontrast-induced nephropathy group according to many risk factors, and the results were significant according to approach with the agreement with Vuurmans et al.[14] This study showed that the age was significant concerning the occurrence of contrast-induced nephropathy and this was in agreement with Shacham et al., who found that there was a significant difference regarding age between the three groups and the occurrence of acute kidney injury (AKI) after primary PCI in STEMI patients. This study showed that sex and weight are nonsignificant regarding CIN after primary PCI in STEMI. There agreed with Shacham et al., who found that there was no significant difference between the studied groups regarding sex and weight.[20] Regarding hypertension, this study showed significance between the studied groups regarding hypertension, and this was in agreement with Mager et al., who found that there was a significant difference between the studied groups regarding hypertension.[21] There agreed with Khan et al., who found that there was a significant difference between hypertension and the occurrence of contrast-induced nephropathy.[22] This study showed that the relationship between the number of diseased vessels and the occurrence of contrast-induced nephropathy was nonsignificant. This study agreed with Shacham et al., who found that the number of diseased vessels was nonsignificant.[20] This study showed the relationship between the urea, creatinine, and cystatin C among the two groups before the primary PCI, which was nonsignificant for the urea, creatinine, and cystatin C. This agreed with Liu et al., who found that baseline serum creatinine was nonsignificant.[23] This study disagreed with Shacham et al., who found that the baseline serum creatinine was highly significant among the studied groups. This study showed that after the primary PCI, there was a highly significant for the serum creatinine and serum cystatin C. This was agreed with Shacham et al., who found that there was an increase in the serum creatinine and serum urea after the primary PCI. Serum cystatin C was one of the most sensitive renal markers regarding contrast-induced nephropathy in comparison to serum creatinine level.[20] Our results were in agreement with Kato et al., who found that contrast-induced nephropathy occurred in 18 patients, and at a cutoff level of > 1.2 mg/L, serum cystatin C before cardiac catheterization was 94.7% sensitivity and 84.8% specificity for detecting contrast-induced nephropathy. Serum cystatin C was higher in contrast-induced nephropathy patients than in non-CIN patients even before cardiac catheterization.[24] In this study, the level of serum cystatin C >1.3 mg/L as a biomarker for occurrence of contrast-induced nephropathy in acute coronary syndrome (STEMI) patients underwent primary PCI with sensitivity = 100%, specificity = 91.3%, positive predictive value = 58.8%, negative predictive value = 100%, accuracy = 92.3% and AUC = 0.986. This was in agreement with Yong et al., who found that serum cystatin C showed a high predictive power for all-cause AKI that the AUC was 0.89.[25] Our results in agreement with Wang et al., who found that the concentration change of serum cystatin C is better than serum creatinine as a biomarker in the early detection of CIN.[26] And also in agreement with Hu et al who found that ROC analysis of serum cystatin C and serum creatinine with AUC (0.859, 0.664), the sensitivity (90.5%, 47.6%) and the specificity (76.2%, 81.0%) were respectively within 48 h post PCI.[27] This study was disagreement with Ribichini et al., who found that an additional diagnostic value of serum cystatin-C over the determination of serum creatinine in the setting of CIN was not observed.[28]


  Conclusion Top


The transradial approach for primary PCI is an effective and safe approach alternative to the femoral approach. The serum cystatin C is a biomarker and a predictor of the occurrence of contrast-induced nephropathy in STEMI patients who underwent primary PCI and is one of the most sensitive renal markers regarding CIN in comparison to serum creatinine level.

Recommendation

This study recommends using the radial approach in primary PCI in the alternative to the femoral approach due to the low incidence of AKI and developing contrast-induced nephropathy and also low local vascular complications.

Limitations

a small number of patient's groups and single-center study.

Acknowledgments

We would like to thank all patients and staff of the Cardiology Department and Cath Lab for participation in this research work.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Barrett BJ, Parfrey PS. Clinical practice. Preventing nephropathy induced by contrast medium. N Engl J Med 2006;354:379-86.  Back to cited text no. 1
    
2.
Chong E, Poh KK, Liang S, Soon CY, Tan HC. Comparison of risks and clinical predictors of contrast-induced nephropathy in patients undergoing emergency versus nonemergency percutaneous coronary interventions. J Interv Cardiol 2010;23:451-9.  Back to cited text no. 2
    
3.
Saito S, Tanaka S, Hiroe Y, Miyashita Y, Takahashi S, Tanaka K, et al. Comparative study on transradial approach vs. transfemoral approach in primary stent implantation for patients with acute myocardial infarction: Results of the test for myocardial infarction by prospective unicenter randomization for access sites (TEMPURA) trial. Catheter Cardiovasc Interv 2003;59:26-33.  Back to cited text no. 3
    
4.
Roos JF, Doust J, Tett SE, Kirkpatrick CM. Diagnostic accuracy of cystatin C compared to serum creatinine for the estimation of renal dysfunction in adults and children – A meta-analysis. Clin Biochem 2007;40:383-91.  Back to cited text no. 4
    
5.
Roffi M, Patrono C, Collet JP, Mueller C, Valgimigli M, Andreotti F, et al. 2015 ESC guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation: Task force for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation of the European Society of Cardiology (ESC). Eur Heart J 2016;37:267-315.  Back to cited text no. 5
    
6.
Barbeau GR, Arsenault F, Dugas L, Simard S, Larivière MM. Evaluation of the ulnopalmar arterial arches with pulse oximetry and plethysmography: Comparison with the Allen's test in 1010 patients. Am Heart J 2004;147:489-93.  Back to cited text no. 6
    
7.
Martin TN, Groenning BA, Murray HM, Steedman T, Foster JE, Elliot AT, et al. ST-segment deviation analysis of the admission 12-lead electrocardiogram as an aid to early diagnosis of acute myocardial infarction with a cardiac magnetic resonance imaging gold standard. J Am Coll Cardiol 2007;50:1021-8.  Back to cited text no. 7
    
8.
Nagueh SF, Smiseth OA, Appleton CP, Byrd BF 3rd, Dokainish H, Edvardsen T, et al. Recommendations for the evaluation of left ventricular diastolic function by echocardiography: An update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging. J Am Soc Echocardiogr 2016;29:277-314.  Back to cited text no. 8
    
9.
Apple FS, Wu AH, Mair J, Ravkilde J, Panteghini M, Tate J, et al. Future biomarkers for detection of ischemia and risk stratification in acute coronary syndrome. Clin Chem 2005;51:810-24.  Back to cited text no. 9
    
10.
Marenzi G, Lauri G, Assanelli E, Campodonico J, De Metrio M, Marana I, et al. Contrast-induced nephropathy in patients undergoing primary angioplasty for acute myocardial infarction. J Am Coll Cardiol 2004;44:1780-5.  Back to cited text no. 10
    
11.
Levine GN, Bates ER, Blankenship JC, Bailey SR, Bittl JA, Cercek B, et al. 2015 ACC/AHA/SCAI focused update on primary percutaneous coronary intervention for patients with ST-elevation myocardial infarction: An update of the 2011 ACCF/AHA/SCAI guideline for percutaneous coronary intervention and the 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction. J Am Coll Cardiol 2016;67:1235-50.  Back to cited text no. 11
    
12.
Seldinger SI. Catheter replacement of the needle in percutaneous arteriography; a new technique. Acta Radiol 1953;39:368-76.  Back to cited text no. 12
    
13.
Shiloh AL, Savel RH, Paulin LM, Eisen LA. Ultrasound-guided catheterization of the radial artery: A systematic review and meta-analysis of randomized controlled trials. Chest 2011;139:524-9.  Back to cited text no. 13
    
14.
Vuurmans T, Byrne J, Fretz E, Janssen C, Hilton JD, Klinke WP, et al. Chronic kidney injury in patients after cardiac catheterisation or percutaneous coronary intervention: A comparison of radial and femoral approaches (from the British Columbia Cardiac and Renal Registries). Heart 2010;96:1538-42.  Back to cited text no. 14
    
15.
Andreucci M, Solomon R, Tasanarong A. Side effects of radiographic contrast media: Pathogenesis, risk factors, and prevention. Biomed Res Int 2014;2014:741018.  Back to cited text no. 15
    
16.
Pancholy S, Patel T, Sanghvi K, Thomas M, Patel T. Comparison of door-to-balloon times for primary PCI using transradial versus transfemoral approach. Catheter Cardiovasc Interv 2010;75:991-5.  Back to cited text no. 16
    
17.
Louvard Y, Ludwig J, Lefèvre T, Schmeisser A, Brück M, Scheinert D, et al. Transradial approach for coronary angioplasty in the setting of acute myocardial infarction. Catheter Cardiovasc Interv 2002;55:206-11.  Back to cited text no. 17
    
18.
Louvard Y, Ludwig J, Lefèvre T, Schmeisser A, Brück M, Scheinert D, et al. Transradial approach for coronary angioplasty in the setting of acute myocardial infarction: A dual-center registry. Catheter Cardiovasc Interv 2002;55:206-11.  Back to cited text no. 18
    
19.
Archbold RA, Robinson NM, Schilling RJ, Radial artery access for coronary angiography and percutaneous coronary intervention BMJ. 2004;329: 443-6.  Back to cited text no. 19
    
20.
Shacham Y, Leshem-Rubinow E, Gal-Oz A, Arbel Y, Keren G, Roth A, et al. Acute cardio-renal syndrome as a cause for renal deterioration among myocardial infarction patients treated with primary percutaneous intervention. Can J Cardiol 2015;31:1240-4.  Back to cited text no. 20
    
21.
Mager A, Vaknin Assa H, Lev EI, Bental T, Assali A, Kornowski R, et al. The ratio of contrast volume to glomerular filtration rate predicts outcomes after percutaneous coronary intervention for ST-segment elevation acute myocardial infarction. Catheter Cardiovasc Interv 2011;78:198-201.  Back to cited text no. 21
    
22.
Khan R, Al-Hawwas M, Hatem R, Azzalini L, Fortier A, Joliecoeur EM, et al. Prognostic impact of the residual SYNTAX score on in-hospital outcomes in patients undergoing primary percutaneous coronary intervention. Catheter Cardiovasc Interv 2016;88:740-7.  Back to cited text no. 22
    
23.
Liu YH, Tan N, Liu Y, Ye P, He YT, Ran P, et al. The relationship between hyperuricemia and contrast-induced nephropathy in patients with chronic kidney disease undergoing percutaneous coronary intervention. Chin Med Assoc House 2013;41:740-3.  Back to cited text no. 23
    
24.
Kato K, Sato N, Yamamoto T, Iwasaki YK, Tanaka K, Mizuno K, et al. Valuable markers for contrast-induced nephropathy in patients undergoing cardiac catheterization. Circ J 2008;72:1499-505.  Back to cited text no. 24
    
25.
Yong Z, Pei X, Zhu B, Yuan H, Zhao W. Predictive value of serum cystatin C for acute kidney injury in adults: A meta-analysis of prospective cohort trials. Sci Rep 2017;7:41012.  Back to cited text no. 25
    
26.
Wang M, Zhang L, Yue R, You G, Zeng R. Significance of cystatin C for early diagnosis of contrast-induced nephropathy in patients undergoing coronary angiography. Med Sci Monit 2016;22:2956-61.  Back to cited text no. 26
    
27.
Hu JT, Xie XL, Tang ZH, Li CQ, Zhou HW. Value of creatinine clearance rate estimated based on serum cystatin C in patients with acute kidney injury. Chin Crit Care Med 2012;24:534-7.  Back to cited text no. 27
    
28.
Ribichini F, Gambaro G, Graziani MS, Pighi M, Pesarini G, Pasoli P, et al. Comparison of serum creatinine and cystatin C for early diagnosis of contrast-induced nephropathy after coronary angiography and interventions. Clin Chem 2012;58:458-64.  Back to cited text no. 28
    


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  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



 

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