Use of the Contrast Volume to Estimated Creatinine Clearance Ratio to Predict Renal Failure After Angiography

Absolute and relative GFR and contrast medium dose/GFR ratio: cornerstones when predicting the risk of acute kidney injury

Glomerular filtration rate (GFR) is considered the best overall index of kidney function in health and disease and its use is recommended to evaluate the risk of iodine contrast medium-induced acute kidney injury (CI-AKI) either as a single parameter or as a ratio between the total contrast medium dose (gram iodine) and GFR. GFR may be expressed in absolute terms (mL/min) or adjusted/indexed to body surface area, relative GFR (mL/min/1.73 m2). Absolute and relative GFR have been used interchangeably to evaluate the risk of CI-AKI, which may be confusing and a potential source of errors. Relative GFR should be used to assess the GFR category of renal function as a sign of the degree of kidney damage and sensitivity for CI-AKI. Absolute GFR represents the excretion capacity of the individual and may be used to calculate the gram-iodine/absolute GFR ratio, an index of systemic drug exposure (amount of contrast medium in the body) that relates to toxicity. It has been found to be an independent predictor of AKI following percutaneous coronary angiography and interventions but has not yet been fully validated for computed tomography (CT). Prospective studies are warranted to evaluate the optimal gram-iodine/absolute GFR ratio to predict AKI at various stages of renal function at CT. Only GFR estimation (eGFR) equations based on standardized creatinine and/or cystatin C assays should be used. eGFRcystatin C/eGFRcreatinine ratio < 0.6 indicating selective glomerular hypofiltration syndrome may have a stronger predictive power for postcontrast AKI than creatinine-based eGFR. CLINICAL RELEVANCE STATEMENT: Once the degree of kidney damage is established by estimating relative GFR (mL/min/1.73 m2), contrast dose in relation to renal excretion capacity [gram-iodine/absolute GFR (mL/min)] may be the best index to evaluate the risk of contrast-induced kidney injury. KEY POINTS: • Relative glomerular filtration rate (GFR; mL/min/1.73 m2) should be used to assess the GFR category as a sign of the degree of kidney damage and sensitivity to contrast medium-induced acute kidney injury (CI-AKI). • Absolute GFR (mL/min) is the individual's actual excretion capacity and the contrast-dose/absolute GFR ratio is a measure of systemic exposure (amount of contrast medium in the body), relates to toxicity and should be expressed in gram-iodine/absolute GFR (mL/min). • Prospective studies are warranted to evaluate the optimal contrast medium dose/GFR ratio predicting the risk of CI-AKI at CT and intra-arterial examinations.

Contrast Media Volume to Creatinine Clearance Ratio in Predicting Nephropathy in Patients Undergoing Percutaneous Coronary Intervention: A Systematic Review and Meta-Analysis

The studies investigated the predictive value of the contrast media volume to creatinine clearance ratio (V/CrCl) for contrast-induced nephropathy (CIN) after a percutaneous coronary intervention (PCI) showed conflicting results and different cut-off values. The objective is to evaluate V/CrCl in the prediction of CIN after PCI. PubMed, Embase, and the Cochrane library were searched for eligible studies published from inception to November 2020. The optimal cut-off points of V/CrCl for predicting CIN were examined using odds ratios (ORs) and 95% confidence intervals (CIs). The random-effect model was used for analyses. Six studies (8 datasets, 16 899 patients) were included. V/CrCl was associated with CIN (OR = 2.67, 95% CI: 1.88-3.78, P < .001; I² = 79.3%, P_{heterogeneity} < .001). V/CrCl was associated with CIN in Asians (OR = 2.13, 95% CI: 1.52-2.98, P = .022; I² = 68.8%, P_{heterogeneity} < .001) and Europeans (OR = 3.87, 95% CI: 1.77-8.45, P < .001; I² = 85.1%, P_{heterogeneity} = .001). The association between V/CrCl and CIN was observed in the prospective cohort studies (OR = 2.16, 95% CI: 1.42-3.29, P = .009; I² = 78.9%, P_{heterogeneity} < .001) and retrospective cohort studies (OR = 3.31, 95% CI: 1.82-6.02, P < .001; I² = 80.6%, P_{heterogeneity} < .001). The sensitivity analysis showed the results were robust. V/CrCl is independently associated with an increased risk of CIN. V/CrCl could be considered a reliable predictor for the development of CIN in patients undergoing PCI.

Safe Limits of Contrast Media for Contrast-Induced Nephropathy: A Multicenter Prospective Cohort Study

Background: The safe level of contrast media volume (CV) is an important modifiable risk factor for contrast-induced nephropathy (CIN). The safe limit of CV remains unclear and is limited to single-center studies. Our objective was to determine the association between the ratio of contrast volume-to-glomerular filtration (CV/GFR) and CIN in patients undergoing coronary angiography (CAG) or percutaneous coronary intervention (PCI). Methods: We assessed the association between CV/GFR and the risk of CIN in 4,254 patients undergoing CAG or PCI from the year 2013 to 2016 and enrolled in the REICIN (REduction of rIsk for Contrast-Induced Nephropathy), a prospective, multicenter, observational cohort study. CV/GFR was calculated at the five primary GFR equation. Results: Sixty-nine (1.7%) patients with a median contrast volume-to-chronic kidney disease epidemiology collaboration (CV/CKD-EPI) ratio of 2.16 (1.30-3.93) have suffered from CIN. The CV/CKD-EPI demonstrated the best performance of model fit, discrimination (area under curve = 0.736), calibration, reclassification, and equation conciseness (1 variable). The CV/CKD-EPI ≥1.78 was the statistical significance associated with CIN [adjusted odds ratio, 4.64 (2.84-7.56); p < 0.001]. Furthermore, similar results were found in the subgroup analyses. Conclusions: The CV/CKD-EPI showed the best performance in patients undergoing CAG or PCI. CV/CKD-EPI ≥1.78 could be a more reliable and convenient predictor of CIN. Intraprocedural preventive measures should include a priori calculation of CV/GFR to limit contrast volume.

The effect of establishing pre-angiography thresholds on contrast utilization

INTRODUCTION

Contrast induced nephropathy is linked to contrast utilization and strategies for minimizing renal injury are incorporated into many laboratories that perform coronary angiography. Contrast limits have been described, below which there is minimal incremental increase in the risk of renal injury. Whether a priori acknowledgement of these limits as part of a contrast "Time-Out" reduces contrast utilization has not been established. In this study, we investigate the effect of verbalizing pre-angiography and ½ time contrast thresholds on contrast utilization and associated clinical outcomes.

METHODS

We retrospectively reviewed 5265 cases of coronary angiography (984 with contrast thresholds defined pre-procedure compared to 4281 without pre-defined contrast thresholds). There were two primary endpoints: (1) proportion of procedures that utilized an amount of contrast ≤ threshold, and (2) median difference between amount of contrast utilized and the contrast threshold. Secondary outcomes incorporated indices of renal function, and included changes in serum creatinine levels, eGFR, and CKD stage.

RESULTS

Compared to pre-"Time-Out" group, the post-"Time-Out" group had a higher proportion of procedures with contrast ≤ stated contrast threshold (88% vs 84%, P < 0.002), and a lower amount of total contrast volume (88 mL [IQR 60-136] versus 78 mL [IQR 53-119]). The post-"Time-Out" group also had a lower incidence of any increase in post-procedure serum creatinine (45% vs 36%; P = 0.04), and a larger median decrease of pre- to post-procedure eGFR (P = 0.04).

CONCLUSION

Acknowledgement of contrast threshold as part of a contrast "Time-Out" is associated with reduced overall contrast utilization, and likely minimizes risks of contrast-induced nephropathy.

Contrast Volume to Cystatin C-Based Glomerular Filtration Ratio Predicts the Risk of Contrast-Induced Nephropathy After Cardiac Catheterization

Cystatin C is considered to be a better alternative to creatinine for estimating glomerular filtration rate (GFR). The aim of this study was to investigate whether a contrast volume to estimated GFR based on cystatin C (V/eGFRcys) is a better predictor of contrast-induced nephropathy (CIN). We enrolled 1195 consecutive patients undergoing elective cardiac catheterization. Receiver–operating characteristic (ROC) curves were used to identify the optimal cutoff value of V/eGFRcys for detecting CIN. Multivariate regression models were used to evaluate whether V/eGFRcys is an independent risk factor for CIN. A total of 19 (1.6%) patients developed CIN. There was a significant association between a higher V/eGFRcys ratio and CIN risk ( P = .008). A ROC curve analysis indicated that a V/eGFRcys ratio of 2.29 was a fair discriminator for CIN. After adjusting for other known CIN risk factors, V/eGFRcys ratios >2.29 remained significantly associated with CIN (odds ratio = 2.93, 95% confidence interval: 1.02-8.44, P = .047). In conclusion, a V/eGFRcys >2.29 was a significant and independent predictor of CIN after cardiac catheterization.

Is the Presence of a Solitary Kidney an Independent Risk Factor for Acute Kidney Injury after Contrast-enhanced CT?

PURPOSE

To determine whether patients with a solitary kidney are at higher risk for contrast material-induced acute kidney injury (AKI) than matched control patients with bilateral kidneys.

MATERIALS AND METHODS

This retrospective study was HIPAA compliant and approved by the institutional review board. Adult patients with bilateral kidneys or a solitary kidney from unilateral nephrectomy who underwent contrast material-enhanced computed tomography (CT) at this institution from January 2004 to August 2013 were identified. The effects of contrast material exposure on the rate of AKI--defined as an increase in maximal observed serum creatinine (SCr) level of either (a) ≥0.5 mg/dL (44.2 μmol/L) or (b) ≥0.3 mg/dL (26.52 μmol/L) or 50% over baseline within 24-72 hours of exposure--and 30-day post-CT emergent dialysis and death were determined after propensity score-based 1:3 matching of patients with solitary kidneys and control patients with bilateral kidneys. Differences in clinical characteristics and outcomes between the solitary and bilateral kidney groups were assessed by using the Wilcoxon rank sum test or Pearson χ(2) test prior to matching and by using conditional logistic regression after matching.

RESULTS

Propensity score matching yielded a cohort of 247 patients with solitary kidneys and 691 patients with bilateral kidneys. The rate of AKI was similar between the solitary and bilateral kidney groups (SCr ≥ 0.5 mg/dL AKI definition odds ratio = 1.11 [95% confidence interval {CI}: 0.65, 1.86], P = .70; SCr ≥ 0.3 mg/dL or 50% over baseline AKI definition odds ratio = 0.96 [95% CI: 0.41, 2.07], P = .99). The rate of emergent dialysis was rare and also similar between cohorts (odds ratio = 1.87 [95% CI: 0.16, 16.4], P = .61). Although the rate of mortality was higher in the solitary kidney group (odds ratio = 1.70 [95% CI: 1.06, 2.71], P = .0202), chart review showed that no death was attributable to AKI.

CONCLUSION

Our study did not demonstrate any significant differences in the rate of AKI, dialysis, or death attributable to contrast-enhanced CT in patients with a solitary kidney versus bilateral kidneys.

Contrast volume to creatinine clearance ratio for the prediction of contrast-induced nephropathy in patients undergoing coronary angiography or percutaneous intervention

BACKGROUND

Contrast-induced nephropathy is a common complication of procedures that are likely to use contrast media. The identification of high-risk patients and preventive optimal hydration are key measures to reduce the incidence of contrast-induced nephropathy. The aim of this study was to evaluate the role of the contrast volume to creatinine clearance ratio (V/CrCl) in the prediction of contrast-induced nephropathy after coronary angiography or percutaneous coronary intervention.

METHODS

Our population consisted of 2308 consecutive patients undergoing coronary angiography and/or percutaneous coronary intervention. The risk of contrast-induced nephropathy was evaluated across quartiles of the V/CrCl. Receiver operating characteristic curves were used to identify the best predictive value. Contrast-induced nephropathy was defined as an absolute increase of 0.5 mg/dL or a relative increase of >25% in creatinine levels 24-48 hours after the procedure.

RESULTS

The total incidence of contrast-induced nephropathy was 12.2% and was significantly higher in the fourth quartile (first quartile 8.8%, second quartile 8.9%, third quartile 11.6% and fourth quartile 19.4%; P < 0.001). Using receiver operating characteristic curves we identified V/CrCl ≥ 6.15 as the best discriminant value for the prediction of contrast-induced nephropathy, which occurred in 25.1% of patients with V/CrCl ≥ 6.15 versus 9.7% in patients with V/CrCl < 6.15. These results were also confirmed at multivariate analysis after correction for all baseline confounders (adjusted odds ratio (AOR) (95% confidence interval (CI)) 1.81 (1.19-2.76); P = 0.005). The association between V/CrCl > 6.15 and an increased risk of contrast-induced nephropathy was confirmed among diabetic (11% vs. 27.7%; p P < 0.001) and non-diabetic patients (8.9% vs. 23%; Pp < 0.001), also after correction for all baseline confounders.

CONCLUSIONS

This is one of the largest studies evaluating the association between the V/CrCl ratio and the risk of contrast-induced nephropathy in patients undergoing coronary angiography or percutaneous coronary intervention. We found that a V/CrCl ratio >6.15 was independently associated with an increased risk of contrast-induced nephropathy.

Predictors of outcomes of contrast-induced acute kidney injury after percutaneous coronary intervention in patients with chronic kidney disease

Contrast-induced acute kidney injury (CI-AKI) is a serious complication that is difficult to predict in patients with chronic kidney disease (CKD) undergoing percutaneous coronary intervention (PCI). The aim of this study was to investigate predictors and clinical outcomes of CI-AKI in patients with CKD after PCI. A total of 297 patients with CKD who underwent PCI from September 2006 to December 2011 were enrolled. CI-AKI was defined as serum creatinine level either ≥25% or ≥0.5 mg/dl from baseline within 72 hours after PCI. The primary outcome was all-cause death. The median follow-up duration was 26 months (interquartile range 12 to 40), and CI-AKI occurred in 55 patients (19%). In multivariate logistic regression analyses, the development of CI-AKI was associated with female gender, left ventricular systolic dysfunction, acute myocardial infarction, PCI for left main disease, serum hemoglobin level, and a contrast volume to creatinine clearance ratio >6.0. The development of CI-AKI was significantly associated with increased in-hospital mortality (18.2% vs 3.7%, p = 0.001). Cox proportional-hazard analysis showed that the incidence of all-cause death was significantly higher in patients who developed CI-AKI than in those without CI-AKI (41.8% vs 16.1%, adjusted hazard ratio 3.0, 95% confidence interval 1.6 to 5.6, p <0.001). In conclusion, female gender, left ventricular systolic dysfunction, acute myocardial infarction, PCI for left main disease, serum hemoglobin level, and contrast volume to creatinine clearance ratio >6.0 are independent predictors of CI-AKI. The development of CI-AKI is significantly associated with increased in-hospital and long-term adverse clinical outcomes in patients with CKD undergoing PCI.

Contrast Volume-to-Creatinine Clearance Ratio Predicts the Risk of Contrast-Induced Nephropathy After Percutaneous Coronary Intervention in Patients With Reduced Ejection Fraction

We determined a relatively safe contrast media volume-to-creatinine clearance (V/CrCl) cutoff value to avoid contrast-induced nephropathy (CIN) after percutaneous coronary intervention (PCI) in patients (n = 111) with reduced ejection fraction (<40%). Improved prediction of CIN in these patients would be useful. Multivariate regression models were used to evaluate whether V/CrCl is an independent risk factor for CIN. Nine (8.1%) patients developed CIN. The V/CrCl was significantly (P = .023) higher in patients with CIN than in those without. The incidence of CIN in patients with the highest tertile of V/CrCl was significantly higher than the middle and lowest tertiles (18.4% vs. 2.7% and 2.8%; P = .013). After adjusting for other potential risk factors, a V/CrCl ≥3.87 remained significantly associated with risk of CIN. A V/CrCl <3.87 might be valuable in predicting the risk of CIN in patients with reduced ejection fraction undergoing PCI.

Safety margin of minimized contrast volume during percutaneous coronary intervention in patients with chronic kidney disease

Maximum allowable contrast dose (MACD) calculated as body weight × 5/serum creatinine has been a standard contrast dye volume (CV) used to decrease contrast-induced acute kidney injury. Recent advances in intravascular ultrasound-guided percutaneous coronary intervention (PCI) can dramatically minimize CV. The safe threshold when using an extremely low-dose CV is unknown. This study was designed as a multicenter, retrospective study of chronic kidney disease (CKD) patients with estimated glomerular filtration rate (eGFR) <30 ml/min/1.73 m(2) undergoing elective PCI. We divided the patients into three groups according to following criteria: (1) low dose, CV/eGFR ratio <1.0; (2) medium dose, CV/eGFR ratio ≥1 and <MACD; and (3) high dose, CV ≥MACD. A total of 100 patients were enrolled. Average age was 74 ± 8 years, 64 % were male and 48 % were diabetic. Mean baseline eGFR was 22.8 ± 6.0 ml/min/1.73 m(2). CV in the three groups was 15 ± 6 ml (n = 18), 69 ± 39 ml (n = 47) and 224 ± 99 ml (n = 35), respectively. The incidences of CI-AKI were 0, 11 and 23 %, respectively (p = 0.02). All-cause death or introduction of maintenance hemodialysis at 1 year was 0, 13.8 and 31 %, respectively (p = 0.01). Extreme reduction of CV to a CV/eGFR ratio <1.0 may reduce CI-AKI and achieve better clinical outcomes following PCI in patients with severe CKD.

The efficacy of the cystatin C based glomerular filtration rate in the estimation of safe contrast media volume

Background and Objectives

The risk of contrast-induced nephropathy (CIN) is significantly influenced by baseline renal function and the amount of contrast media (CM). We evaluated the usefulness of the cystatin C (CyC) based estimated glomerular filtration rate (eGFR_CyC) in the prediction of CIN and to determine the safe CM dosage.

Subjects and Methods

We prospectively enrolled a total of 723 patients who received percutaneous coronary intervention (PCI) and investigated the clinical factors associated with the development of CIN. Renal function was calculated as eGFR_CyC and a modified diet in the renal disease (MDRD) equation, respectively. Systemic exposure of CM was calculated as CM volume to eGFR ratio. We conducted a regression analysis to evaluate the predictive role of CM volume to eGFR_CyC for the risk of CIN.

Results

The incidence of CIN was 4.0% (29/723). The patients with CIN had a lower hemoglobin level, decreased renal function, and a higher CyC value, and had greater CM exposure. Through multivariate regression analyses, hemoglobin {odds ratio (OR) 0.743, p=0.032}, CM volume/eGFR_CyC (OR 1.697, p=0.006) and CM volume/MDRD (OR 2.275, p<0.001) were found to be independent predictors for CIN. In the receiver operating characteristic curve analysis, fair discrimination for CIN was found at a CM volume/eGFR_CyC level of 4.493 (C-statics=0.814), and at this value, the sensitivity and specificity were 79.3% and 80.0%, respectively.

Conclusion

Both the CM volume/MDRD and CM volume/eGFR_CyC method would be simple, useful indicators for determining the safe CM-dose based on eGFR value before PCI. However, there was no significantly different predictive value between creatinine and CyC based GFR estimations.

Use of the contrast volume or grams of iodine-to-creatinine clearance ratio to predict mortality after percutaneous coronary intervention

BACKGROUND

Few studies have assessed the predictive value of the ratio of the contrast media volume or grams of iodine to the creatinine clearance (V/CrCl or g-I/CrCl, respectively) for the risk of contrast-induced nephropathy (CIN) and mortality after percutaneous coronary intervention (PCI).

METHODS

The association between V/CrCl and mortality was prospectively evaluated in 1,135 consecutive patients undergoing PCI. Cox regression models were used to adjust for the V/CrCl ratio and other confounding factors for risk of death within 1 year.

RESULTS

Fifty-five patients (4.84%) developed CIN. The 1-year mortality was higher in patients with a V/CrCl ratio >2.62 (g-I/CrCl >0.97) than in others (4.44% vs 0.40%; P < .001). After adjusting for other risk factors, the 1-year mortality risk remained associated with increased V/CrCl ratio. The risk of death was significant for V/CrCl >2.62 (adjusted risk ratio [RR] for death 2.605, 95% CI 1.040-6.529, P = .041), V/CrCl >3.0 (g-I/CrCl >1.11) (adjusted RR 4.338, 95% CI 1.689-11.142, P = .002), and V/CrCl >3.7 (g-I/CrCl >1.37) (adjusted RR 2.557, 95% CI 1.162-5.627, P = .002).

CONCLUSION

The data further support the prognostic significance of calculating the V/CrCl ratio to predict the relative maximum contrast volume during PCI. Use of a contrast dose determined based on the estimated renal function with a planned V/CrCl ratio <3.7 (g-I/CrCl <1.37) and preferably <2.62 (g-I/CrCl <0.97) might be valuable in reducing the risks of CIN and even death after PCI.

Contrast medium volume to creatinine clearance ratio: a predictor of contrast-induced nephropathy in the first 72 hours following percutaneous coronary intervention

OBJECTIVES

To investigate the predictive value of the contrast media volume to creatinine clearance (V/CrCl) ratio for the risk of contrast-induced nephropathy (CIN) (i.e., within 48-72 hr) and to determine a relatively safe V/CrCl cut-off value to avoid CIN in patients following percutaneous coronary intervention (PCI).

BACKGROUND

The V/CrCl ratio is a pharmacokinetic risk factor for an early abnormal increase in serum creatinine (i.e., within 24 hr) after PCI.

METHODS

V/CrCl ratios were obtained from 1,140 consecutive consenting patients after unselective PCI. Receiver-operator characteristic (ROC) curves were used to identify the optimal sensitivity for the observed range of V/CrCl. The predictive value of V/CrCl for the risk of CIN was assessed using multivariate logistic regression.

RESULTS

Fifty-five (4.8%) patients out of 1,140 developed CIN. There was a significant association between higher V/CrCl ratio values and risk of CIN in the overall population: 1.4%, 1.4%, 5.7%, and 10.9% for quartile 1 (Q1) of the V/CrCl value (<1.56, n = 283), Q2 (1.56-2.27, n = 289), Q3 (2.28-3.42, n = 282), and Q4 (>3.42, n = 285) of contrast, respectively (P < 0.001). ROC curve analysis indicated that a V/CrCl ratio of 2.62 was a fair discriminator for CIN (C-statistic 0.73). After adjusting for other known predictors of CIN, V/CrCl ratios > 2.62 remained significantly associated with CIN (odds ratio: 2.20; 95% confidence interval: 1.00-4.81, P < 0.05).

CONCLUSION

A V/CrCl ratio > 2.62 was a significant and independent predictor of CIN after PCI in unselected patients.

Determination of safe contrast media dosage to estimated glomerular filtration rate ratios to avoid contrast-induced nephropathy after elective percutaneous coronary intervention

Background and Objectives

To avoid the risk of developing contrast-induced nephropathy (CIN), it has been suggested that patients be subjected to a minimal necessary dose of contrast medium (CM-dose). However, often it is not easy to determine such a dose. This study assessed the usefulness of the ratio of CM-dose to estimated glomerular filtration rate (eGFR) in predicting the risks of CIN and sought to determine the safe level of CM-dose/eGFR in patients undergoing non-emergent percutaneous coronary intervention (PCI).

Subjects and Methods

We enrolled a total of 226 patients and calculated the ratio of CM-dose using grams of iodine (g-I) to eGFR, thus expressing it as g-I/eGFR. Among the CIN patients, those with ne-phropathy requiring dialysis (NRD) were also evaluated.

Results

Overall, there were 16 cases (7.1%) of CIN. On univariate and multivariate regression analysis, g-I/eGFR alone was found to be an independent predictor for CIN (hazard ratio=10.73, p<0.001). In an receiver operating characteristic analysis, fair discrimination for CIN was found at a g-I/eGFR level of 1.42 (C statics=0.867), and at this value, the sensitivity and specificity were 81.3% and 80%, respectively. Of patients (n=51) with g-I/eGFR ≥1.42, 23.6% (13/51) and 7.8% (4/51) developed, while those with g-I/eGFR <1.42 (n=171) had a lower incidences of CIN (1.8%, 2/171, p<0.001) and NRD (0%, 0/171, p<0.001).

Conclusion

It can be concluded that a g-I/eGFR <1.42 is a simple, useful indicator for determining the safe CM-dose based on the pre-PCI eGFR values. Furthermore, g-I/eGFR might have a close relationship with the development of NRD as well as CIN.

The contrast medium volume to estimated glomerular filtration rate ratio as a predictor of contrast-induced nephropathy after primary percutaneous coronary intervention

BACKGROUND

Contrast-induced nephropathy (CIN) is a serious complication in percutaneous coronary intervention (PCI) patients, which may be related to the contrast dose used during cardiac catheterization.

METHODS

We prospectively investigated 277 consecutive consenting patients with acute ST-segment elevation myocardial infarction (STEMI) who were given primary PCI, and we calculated their ratio of volume of contrast media to estimated glomerular filtration rate (V/eGFR). Receiver-operator characteristic methods were used to identify the optimal sensitivity for the observed range of V/eGFR for CIN (i.e., within 48-72 h). The predictive value of V/eGFR for the risk of CIN was assessed using multivariable logistic regression.

RESULTS

Twenty-five (9%) patients developed CIN. The baseline mean and median V/eGFR values were significantly greater among patients with CIN (mean 3.22 ± 1.53, median 2.97, and interquartile range 1.90-4.17) than among those without CIN (mean 1.80 ± 1.00, median 1.52, and interquartile range 1.12-2.21, P < 0.001). The receiver-operator characteristic curve analysis indicated that a V/eGFR ratio of 2.39 was a fair discriminator for CIN (C statistic 0.81). After adjusting for other known predictors of CIN, a V/eGFR ratio ≥ 2.39 remained significantly associated with CIN (odds ratio 4.24, 95% confidence interval 1.23-14.66, P < 0.05).

CONCLUSION

A V/eGFR ratio ≥ 2.39 was a significant and independent predictor of CIN after primary PCI in patients with STEMI.

Risk of nephropathy is not increased by the administration of larger volume of contrast during coronary angiography

It is proposed that contrast-induced nephropathy (CN) correlates with the use of increasing contrast volumes during coronary angiography. This supposition has led to the current recommendation to limit the dose of contrast in patients at high risk for renal dysfunction. Limits in contrast dosing may negatively impact the evaluation of patients undergoing cardiac catheterization for myocardial infarction and acute coronary syndrome. The objective of this study was to empirically assess, in a large population, the presence and strength of this correlation. Baseline blood samples and clinical information were obtained from 5256 consenting patients hospitalized for coronary angiography. Levels of serum creatinine were measured pre- and postcatheterization, and the total change in serum creatinine was calculated. Nephropathy was defined as a change of > or =0.5 mg/dL. The total volume of contrast dye (iopamidol, nonionic) used during the angiography procedure was recorded. Logistic regression was used for the primary analysis.The average age was 64 +/- 14 years, and 67% of patients were male. Paradoxically, the incidence of CN was inversely related to the volume in the overall population: 16%, 14%, 8%, and 7% for quartile (Q) 1 (<115 mL), Q2 (115-160 mL), Q3 (161-225 mL), and Q4 (>225 mL) of contrast, respectively (P-trend <0.001). In multivariable regression, this trend toward lower CN remained (Q1 (referent) OR = 1.0, Q2: 1.02, Q3: 0.60, Q4: 0.53, P < 0.001). Other predictors included age, left ventricular ejection fraction, diabetes, and baseline creatinine level (all P < 0.001). For patients at high risk, with a baseline creatinine >2.0 mg/dL (n = 415), contrast volume (Q1: <75 mL, Q2: 75-120 mL, Q3: 121-170 mL, Q4: >170 mL) did not predict either increased or decreased risk of CN (48%, 42%, 49%, 43%, respectively, P-trend = 0.76). This lack of predictive value remained after multivariable adjustment.In this large population, no association was found between the amount of contrast used during angiography and the incidence of CN in patients at initial high risk. The apparent inverse relation of risk with volume in the overall population is likely explained by clinical practice bias. If confirmed, these results may have important clinical implications.

Contrast medium volume to estimated glomerular filtration rate ratio as a predictor of contrast-induced nephropathy developing after elective percutaneous coronary intervention

BACKGROUND

Contrast-induced nephropathy (CIN) has been recognized as a serious complication of diagnostic coronary angiography and percutaneous coronary intervention (PCI), and has been associated with prolonged hospitalization and adverse clinical outcomes. A key step to minimize the risk for developing CIN is to identify patients at risk for CIN.

METHODS AND RESULTS

We retrospectively investigated clinical factors associated with the development of CIN in 60 stable angina patients who had undergone elective PCI. The frequency of CIN was 13% (8/60). There were neither any significant differences in age, gender, baseline serum creatinine or hemoglobin levels, nor in the rate of diabetes mellitus between the CIN and the non-CIN group. However, the estimated glomerular filtration rate (eGFR) was significantly lower (40.4+/-11.4 mL/min/1.73 m(2) vs. 57.4+/-22.6 mL/min/1.73 m(2), p=0.044), and number of treated vessels (1.5+/-0.8 vs. 1.2+/-0.4, p=0.039) and stents used (2.1+/-0.6 vs. 1.4+/-0.6, p=0.007) were significantly higher in the CIN group. In addition, the amount of contrast medium was significantly larger (272+/-37 mL vs. 201+/-62 mL, p=0.003) and the contrast medium volume (CMV) to eGFR ratio (CMV/eGFR) was significantly greater (7.4+/-2.9 vs. 4.0+/-2.0, p=0.0001) in the CIN group. Stepwise regression analysis showed that the CMV/eGFR ratio was a significant independent predictor of CIN (p=0.035). At a cut-off point of >5.1, the CMV/eGFR ratio exhibited 87.5% sensitivity and 74.5% specificity for detecting CIN.

CONCLUSION

The CMV/eGFR ratio could be a useful predictor of CIN developing after elective PCI.

Volume-to-creatinine clearance ratio: a pharmacokinetically based risk factor for prediction of early creatinine increase after percutaneous coronary intervention

OBJECTIVES

This study sought to validate a pharmacokinetically derived measure of the risk of an early increase in serum creatinine after percutaneous coronary intervention (PCI).

BACKGROUND

The ratio of the volume of contrast media to the creatinine clearance (V/CrCl) has been shown to correlate with the area under the curve of contrast media concentration over time.

METHODS

We calculated V/CrCl in 3,179 consecutive patients undergoing PCI. An increase in serum creatinine of >0.5 mg/dl by 24 to 48 h was considered abnormal. Receiver-operator characteristic methods were used to identify the optimal sensitivity and specificity for the observed range of V/CrCl. The predictive value of V/CrCl for the risk of an early increase in creatinine was assessed using multivariable logistic regression.

RESULTS

The overall incidence of an abnormal, early increase in creatinine was 1.5%. The mean and median values of V/CrCl for patients with (mean 5.2 +/- 4.4, median 4.3, interquartile range 2.7 to 6.0) and without (mean 3.0 +/- 2.0, median 2.5, interquartile range 1.7 to 3.8) an early creatinine increase were each significantly (p < 0.001) different between groups. Furthermore, there was a significant association between V/CrCl and an early increase in creatinine (overall and trend, p < 0.001). The receiver-operator characteristic curve analysis indicated that a V/CrCl ratio of 3.7 was a fair discriminator for the early creatinine increase (C-statistic 0.69). After adjusting for other known predictors of post-PCI creatinine increase, V/CrCl > or =3.7 remained significantly associated with an early abnormal increase in serum creatinine (odds ratio 3.84; 95% confidence interval 2.0 to 7.3, p < 0.001).

CONCLUSIONS

A V/CrCl ratio >3.7 was a significant and independent predictor of an early abnormal increase in serum creatinine after PCI in this unselected patient population.

Contrast medium use

Various properties of iodinated contrast media (osmolality, ionic versus nonionic, and viscosity) may contribute to contrast-induced nephropathy (CIN). Therefore, the choice of contrast medium affects the risk for CIN. There is good evidence that low-osmolar contrast media are less nephrotoxic than high-osmolar contrast media in patients at increased risk for CIN who receive intra-arterial iodinated contrast. Current evidence suggests that nonionic isosmolar contrast presents the lowest risk for CIN in patients with chronic kidney disease (CKD), particularly in those patients with diabetes mellitus. Intra-arterial administration of contrast media may be associated with a greater risk for CIN above that observed with intravenous administration. The use of gadolinium or CO(2) as alternative contrast media to avoid the risk of nephrotoxicity cannot be substantiated by clinical trials and therefore cannot be recommended. Most studies show that, within a class, higher volumes (>100 mL) of iodinated contrast medium are associated with a higher risk for CIN. However, in patients at high risk, such as those with CKD and diabetes, even small volumes of contrast medium can have adverse effects on renal function.