Contrast Dose-to-Creatinine Clearance Ratio as a Potential Indicator of Risk for Radiocontrast-Induced Nephropathy

Outcomes of ultra-low contrast percutaneous coronary intervention in patients with advanced chronic kidney disease

BACKGROUND

Coronary angiography and percutaneous coronary intervention (PCI) in patients with chronic kidney disease (CKD) is associated with increased risk of contrast induced nephropathy (CIN) and requirement for renal replacement therapy (RRT).

OBJECTIVES

We aimed to evaluate our single center experience of ultra-low contrast PCI in patients with CKD and to characterize 1 year outcomes.

METHODS

We performed a retrospective analysis of ultra-low contrast PCI at our institution between 2016 and 2022. Patients with CKD3b-5 (eGFR <45 mL/min/1.73m2), not on RRT who underwent ultra-low contrast PCI ( < 30 mL of contrast during PCI) were included. Primary outcomes included change in eGFR post-procedurally, and death, RRT requirement, and major adverse cardiac events (MACE) at 1 year follow-up.

RESULTS

One hundred patients were included in the study. The median age was 67 years old and 28% were female. The median baseline eGFR was 21.5 mL/min/1.73m2 (IQR 14.08-32.0 mL/min/1.73m2). A median of 8.0 mL (IQR 0-15 mL) of contrast was used during PCI. Median contrast use to eGFR ratio was 0.37 (IQR 0-0.59). There was no significant difference between pre-and postprocedure eGFR (p = 0.84). At 1 year, 8% of patients died, 11% required RRT and 33% experienced MACE. The average time of RRT initiation was 7 months post-PCI. Forty-four patients were undergoing renal transplant evaluation, of which 17 (39%) received a transplant.

CONCLUSIONS

In patients with advanced CKD, ultra-low contrast PCI is feasible and safe with minimal need for peri-procedural RRT. Moreover, ultra-low contrast PCI may allow for preservation of renal function in anticipation of renal transplantation.

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.

Revised Swedish guidelines on intravenous iodine contrast medium-induced acute kidney injury 2022: A summary

The Swedish Society of Uroradiology has revised their computed tomography (CT) guidelines regarding iodine contrast media-induced acute kidney injury (CI-AKI). They are more cautious compared to the European Society of Urogenital Radiology and the American College of Radiology since the actual risk of CI-AKI remains uncertain in patients with moderate to severe kidney damage due to a lack of prospective controlled studies and mainly based on retrospective propensity score-matched studies with low-grade evidence. Another source of uncertainty is the imprecision of glomerular filtration rate (GFR) estimating equations. However, randomized hydration studies indictae an upper limit risk of CI-AKI of about 5% for outpatients with a GFR in the range of 30-44 or 45-59 mL/min/1.73m² combined with multiple risk factors. Apart from GFR limits, the guideline also includes limits for systemic contrast medium exposure expressed in gram-iodine/GFR ratio.

The Target Vessel SYNTAX Score: A Novel Pre-Procedural Predictor for Contrast-Induced Acute Kidney Injury After Rotational Atherectomy

BACKGROUND

Rotational atherectomy (RA) is a complex procedure often associated with high contrast load. Known risk scores do not predict contrast-induced acute kidney injury (CI-AKI) before RA. We aim to investigate pre-procedural predictors of CI-AKI after RA, and the role of the target vessel SYNTAX score (tvSS).

METHODS

Among 295 patients who underwent RA between 01.2010 and 02.2019 at a single center, 49 developed CI-AKI. Those who were on chronic hemodialysis or with no available 48-h' kidney function tests were excluded. Predictors of CI-AKI were assessed in the whole cohort and those with no basal renal impairment.

RESULTS

The rate of CI-AKI was 16.6 %. The tvSS was 18 [14-23] vs. 12 [9-18] in patients with vs. without CI-AKI (p < 0.001). The tvSS cut-off value of 15 provided 75 % sensitivity and 60 % specificity for predicting CI-AKI. Consequently, a tvSS ≥15 emerged as an independent pre-procedural predictor for CI-AKI (adjusted OR: 4.94, 95 % CI: 2.38-10.20, p < 0.001), along with left ventricular ejection fraction (LVEF) ≤35 % (p = 0.016) and glomerular filtration rate (GFR) <45 ml/min (p = 0.004). TvSS was the only independent pre-procedural predictor for CI-AKI in patients with GFR ≥60 ml/min (p < 0.001). The contrast volume/GFR ratio and peri-procedural myocardial infarction (MI) were independent procedural predictors for CI-AKI in the whole cohort and in patients with basal GFR ≥60 ml/min.

CONCLUSION

CI-AKI after RA is frequent. The tvSS is an efficient pre-procedural predictor for CI-AKI after RA, along with LVEF ≤35 % and GFR <45 ml/min. Contrast volume/GFR ratio and peri-procedural MI emerged as procedural predictors for CI-AKI.

Association Between Contrast Volume-to-Creatinine Clearance Ratio and the Risk of Perioperative Myocardial Infarction After Elective Percutaneous Coronary Intervention

Although the use of iodinated contrast for percutaneous coronary intervention (PCI) has known toxicity issues, the association between the contrast volume-to-creatinine clearance (V/CrCl) ratio and perioperative myocardial infarction (PMI) is unclear. The present study is aimed to investigate the predictive value of V/CrCl ratio on the incidence of PMI, and to determine a relatively safe contrast media V/CrCl ratio cut-off value to prevent PMI undergoing elective PCI. The V/CrCl ratio were obtained from 5970 patients undergoing elective PCI for single-vessel lesions. Cardiac troponin I (cTnI) were measured at baseline, 8, 16, and 24 hours after PCI. PMI was defined as postprocedural > 5 × upper limit of normal. Receiver operating characteristic (ROC) curves were performed to identify the optimal sensitivity for the V/CrCl range. Multivariate regression model were used to assess the association between V/CrCl ratios and PMI. Eight hundred and ninety-seven patients (15.0%) developed PMI. There was a significant association between higher V/CrCl ratio and the development of PMI (P < 0.001 for the trend). ROC curve analysis indicated that V/CrCl ratio of 2.05 was a discriminator for PMI (area under the curve = 0.674). After adjusting for other potential risk factors, V/CrCl ratio > 2.05 remained significant associated with PMI (odds ratio, 1.921; 95% confidence interval, 1.311-2.815; P = 0.001). The finding of this study suggests the importance of minimizing the contrast media dose to avoid PMI development. Use of a contrast media dose based on renal function with a V/CrCl value < 2.05 might be valuable in preventing PMI.

Ultra-low CONtraSt PCI vs conVEntional PCI in patients of ACS with increased risk of CI-AKI (CONSaVE-AKI)

Objectives

This prospective, randomized study assessed short-term outcomes and safety of ultra-low contrast percutaneous coronary intervention(ULC-PCI) vs conventional PCI in high risk for contrast induced acute kidney injury(CI-AKI) patients presenting with acute coronary syndrome(ACS).

Background

Patients at an increased risk of developing CI-AKI can be identified prior to PCI based on their pre-procedural risk scores. ULC-PCI is a novel contrast conservation strategy in such high risk patients for prevention of CI-AKI.

Methods

82 patients undergoing PCI for ACS were enrolled having estimated glomerular filtration rate(eGFR) < 60 ml/min/1.73 m² and moderate to very high pre-procedural risk of developing CI-AKI as calculated by Maioli risk calculator. They were randomized into two groups of 41 patients each of ULC-PCI (contrast volume ≤ patient's eGFR) and conventional PCI (contrast volume ≤ 3xpatient's eGFR). Primary end point was development of CI-AKI.

Results

Baseline clinical and angiographic characteristics were similar between groups. Primary outcome of CI-AKI occurred more in patients of the conventional PCI group [7 (17.1%)] than in the ULC PCI group [(0 patients), p = 0.012]. Contrast volume (41.02 (±9.8) ml vs 112.54 (±25.18) ml; P < 0.0001) was markedly lower in the ULC-PCI group. No significant difference in secondary safety outcomes between two study arms at 30 days. IVUS was used in 17% patients in ULC PCI.

Conclusion

ULC-PCI in patients with increased risk of developing CI-AKI is feasible, appears safe, and has the potential to decrease the incidence of CI-AKI specially in resource limited setting such as ours where coronary imaging by IVUS is not possible in every patient.

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.

Volume of contrast to creatinine clearance ratio predicts early mortality and AKI after TAVI

The volume of contrast to creatinine clearance ratio (CV/CrCl) is a useful indicator of the risk of acute kidney injury (AKI) in patients undergoing percutaneous interventional procedures. Association between CV/CrCl and adverse outcome after transcatheter aortic valve implantation (TAVI) was suggested but it is not well established. A large retrospective multicenter cohort of 1381 patients treated with TAVI was analyzed to assess the association between CV/CrCl and the risk of AKI and mortality at 90 days and 1 year after TAVI. Patients receiving renal replacement therapy at the time of TAVI were excluded. CV/CrCl ≥ 2.2 was associated with the risk of AKI and 90 days mortality after TAVI after adjustment for age, sex, diabetes, baseline left ventricular function, baseline chronic kidney disease (CKD), previous myocardial infarction and peripheral vascular disease (hazard ratio [HR]: 1.16, 95% confidence interval [CI]: 1.09–1.22, p < 0.0001). Importantly, CV/CrCl was associated with the adverse outcome independently from the presence of baseline CKD (p for interaction = 0.22). CV/CrCl was independently associated with the individual components of the composite primary outcome including AKI (odds ratio: 1.18, 95% CI: 1.08–1.28, p < 0.0001) and 90 days mortality (HR: 1.90, 95% CI: 1.01–3.60, p = 0.047) after TAVI. AKI (HR: 1.94, 95% CI: 1.21–3.11, p = 0.006) but not CV/CrCl was associated with the risk of 1‐year mortality after TAVI. CV/CrCl is associated with excess renal damage and early mortality after TAVI. Procedural strategies to minimize the CV/CrCl during TAVI may improve early clinical outcomes in patients undergoing TAVI.

Use of Contrast Medium Volume to Guide Prophylactic Hydration to Prevent Acute Kidney Injury After Contrast Administration: A Meta-Analysis

OBJECTIVE. The purpose of this study was to determine whether contrast medium volume and method of administration and baseline estimated glomerular filtration rate influence the efficacy of prophylactic hydration for prevention of acute kidney injury after contrast administration. MATERIALS AND METHODS. An online search of PubMed conducted on August 25, 2017, produced a total of 697 studies. After the reports were reviewed, nine were included in this study. The extracted data on all patients in these studies were separated into a group that received prophylactic hydration and a group that did not. The following three parameters were used for subgroup analysis: contrast medium volume, contrast administration method, and baseline estimated glomerular filtration rate. The t test was performed, and study-level odds ratios with 95% CIs and p values were calculated. Tests of heterogeneity were conducted. RESULTS. When the volume of contrast agent administered exceeded 100 mL, hydration was beneficial in the prevention of contrast-induced acute kidney injury (odds ratio, 0.546). If the volume was less than 100 mL, hydration had no efficacy in preventing contrast-induced acute kidney injury (odds ratio, 0.917). Administration route and baseline estimated glomerular filtration rate exerted no effect on the efficacy of prophylactic hydration. CONCLUSION. For patients who receive less than 100 mL of contrast medium, the prevalent practice for contrast-enhanced CT studies, prophylactic hydration may not be necessary, regardless of the estimated glomerular filtration rate or route of contrast administration. For patients undergoing procedures requiring administration of large volumes of contrast medium, however, hydration is recommended to prevent contrast-induced acute kidney injury.

Ultra-low contrast coronary angiography and zero-contrast percutaneous coronary intervention for prevention of contrast-induced nephropathy: step-by-step approach and review

Contrast-induced nephropathy is a serious complication after intravascular administration of iodinated contrast media and is associated with numerous adverse outcomes. Its prevalence is particularly high in patients with multiple comorbidities who undergo coronary angiography and percutaneous coronary intervention (PCI). Currently, the only effective method to prevent contrast-induced kidney injury is adequate hydration and a reduction of contrast volume during the intervention. Recently, new approaches aiming to minimize contrast usage have been proposed, i.e., ultra-low contrast angiography and zero-contrast PCI. However, neither tutorials for these techniques nor reviews of their outcomes exist in the literature, and therefore dissemination of these approaches among the interventional community may be limited. This article presents a step-by-step description on how to perform ultra-low coronary angiography and zero-contrast PCI, which should help invasive cardiologists to adopt these techniques in daily practice. A review of clinical studies, case series and single case reports regarding these methods is also provided. Despite the promising results, such procedures still require some improvements and confirmation of their effectiveness as well as safety in large clinical studies. This article aims to spread these new techniques throughout the interventional community, which is paramount for their further development and wider utilization.

Contrast volume to estimated glomerular filtration rate ratio for prediction of contrast-induced acute kidney injury after cardiac catheterization in adults with congenital heart disease

BACKGROUND

Adults with congenital heart disease (ACHD) are vulnerable to contrast-induced acute kidney injury (CI-AKI) after cardiac catheterization. The aim of this study was to identify risk factors for clinically significant CI-AKI and evaluate the predictive value of contrast volume to estimated glomerular filtration rate ratio (V/eGFR) for the risk of CI-AKI following catheterization in the ACHD population.

METHODS

ACHD patients who underwent catheterization at Boston Children's hospital between 1/2011 and 1/2017 were retrospectively analyzed. CI-AKI was defined as an increase in serum creatinine ≥0.3 mg/dL within 48 hr or ≥1.5 times baseline within 7 days of procedure. Controls without CI-AKI were matched for calendar year of catheterization with cases using a 3:1 ratio.

RESULTS

Of 453 catheterizations meeting inclusion criteria, 27 catheterizations (5.9%) were complicated by CI-AKI, with dialysis being used to manage renal dysfunction in five of these events. Older age, male gender, admission prior to catheterization, and V/eGFR ratio were found to be related to risk of CI-AKI. Patients with a V/eGFR ≥ 2.6 had a significantly higher risk of CI-AKI (OR = 6.4; 95% CI = 2.0-20.4; P = 0.002). Survival at 3 years post-catheterization, was significantly shorter for CI-AKI cases compared to controls (49% versus 97%; P < 0.001) even in those with return to baseline renal function prior to discharge (60% versus 97%, P < 0.001).

CONCLUSION

In ACHD patients undergoing cardiac catheterization, a higher V/eGFR ratio is a strong predictor of clinically significant CI-AKI. Development of CI-AKI is a poor prognostic indicator and is associated with decreased survival in this population.

The predictive value of the product of contrast medium volume and urinary albumin/creatinine ratio in contrast-induced acute kidney injury

Preexisting renal impairment and the amount of contrast media are the most important risk factors for contrast-induced acute kidney injury (CI-AKI). We aimed to investigate whether the product of contrast medium volume and urinary albumin/creatinine ratio (CMV × UACR) would be a better predictor of CI-AKI in patients undergoing nonemergency coronary interventions. This was a prospective single-center observational study, and 912 consecutive patients who were exposed to contrast media during coronary interventions were investigated prospectively. CI-AKI is defined as a 44.2 μmol/L rise in serum creatinine or a 25% increase, assessed within 48 h after administration of contrast media in the absence of other causes. Fifty patients (5.48%) developed CI-AKI. The urinary albumin/creatinine ratio (UACR) (OR = 1.002, 95% CI = 1.000–1.003, p = .012) and contrast medium volume (CMV) (OR = 1.008, 95% CI = 1.001–1.014, p = .017) were independent risk factors for the development of CI-AKI. The area under the ROC curve of CMV, UACR and CMV × UACR were 0.662 (95% CI = 0.584–0.741, p < .001), 0.761 (95% CI = 0.674–0.847, p < .001) and 0.808 (95% CI = 0.747–0.896, p < .001), respectively. The cutoff value of CMV × UACR to predict CI-AKI was 1186.2, with 80.0% sensitivity and 62.2% specificity. The product of CMV and UACR (CMV × UACR) might be a predictor of CI-AKI in patients undergoing nonemergency coronary interventions, which was superior to CMV or UACR alone.

Accuracy of GFR estimating equations in a large Swedish cohort: implications for radiologists in daily routine and research

Background Guidelines recommend estimation of glomerular filtration rate (eGFR) prior to iodine contrast media (CM) examinations. It is also recommended that absolute eGFR in mL/min, not commonly used relative GFR (adjusted to body surface area; mL/min/1.73 m²), should be preferred when dosing and evaluating toxicity of renally excreted drugs. Purpose To validate the absolute Lund-Malmö equation (LM-ABS) in comparison with the absolute Cockcroft-Gault (CG) equation and the relative equations, revised Lund-Malmö (LM-REV), MDRD, and CKD-EPI, after converting relative estimates to absolute values, and to analyze change in eGFR classification when absolute instead of relative eGFR was used. Material and Methods A total of 3495 plasma clearance of iohexol to measure GFR (mGFR) served as reference test. Bias, precision, and accuracy (percentage of estimates ±30% of mGFR; P₃₀) were compared overall and after stratification for various mGFR, eGFR, age, and BMI subgroups. Results The overall P₃₀ results of CG/LM-ABS/LM-REV/MDRD/CKD-EPI were 62.8%/84.9%/83.7%/75.3%/75.6%, respectively. LM-ABS was the most stable equations across subgroups and the only equation that did not exhibit marked overestimation in underweight patients. For patients with relative eGFR 30-44 and 45-59 mL/min/1.73 m², 36% and 58% of men, respectively, and 24% and 32% of women, respectively, will have absolute eGFR values outside these relative eGFR intervals. Conclusion Choosing one equation to estimate GFR prior to contrast medium examinations, LM-ABS may be preferable. Unless absolute instead of relative eGFR are used, systematic inaccuracies in assessment of renal function may occur in daily routine and research on CM nephrotoxicity may be flawed.

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.

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.

Extended renal outcomes with use of iodixanol versus iohexol after coronary angiography

The impact of isoosmolar versus low-osmolar contrast media (CM) administration on contrast-induced acute kidney injury (CI-AKI) and extended renal dysfunction (ERD) is unclear. We retrospectively examined incidences of CI-AKI and ERD in patients who received iodixanol (isoosmolar) versus iohexol (low-osmolar) during angiography for cardiac indications. Of 713 patients, 560 (cohort A), 190 (cohort B), and 172 (cohort C) had serum creatinine monitored at 3 days, 30 days, and 6 months after angiography, respectively. 18% of cohort A developed CI-AKI, which was more common with iodixanol than iohexol (22% versus 13%, P = 0.006). However, patients given iodixanol were older with lower baseline estimated glomerular filtration rates (eGFR). On multivariate analysis, independent associations with higher CI-AKI risk include age >65 years, female gender, cardiac failure, ST-elevation myocardial infarction, intra-aortic balloon pump, and critical illness, but not CM type, higher CM load, or eGFR < 45 mL/min/1.73 m². 32% of cohort B and 34% of cohort C had ERD at 30 days and 6 months, while 44% and 41% of subcohorts had ERD at 90 days and 1 year, respectively. CI-AKI, but not CM type, was associated with medium- and longer-term ERD, with 3-fold higher risk. Advanced age, emergent cardiac conditions, and critical illness are stronger predictors of CI-AKI, compared with CM-related factors. CI-AKI predicts longer-term ERD.

Contrast-induced acute kidney injury: definition, epidemiology, and outcome

Contrast-induced acute kidney injury (CI-AKI) is commonly defined as a decline in kidney function occurring in a narrow time window after administration of iodinated contrast material. The incidence of AKI after contrast material administration greatly depends on the specific definition and cutoff values used. Although self-limiting in most cases, postcontrast AKI carries a risk of more permanent renal insufficiency, dialysis, and death. The risk of AKI from contrast material, in particular when administered intravenously for contrast-enhanced CT, has been exaggerated by older, noncontrolled studies due to background fluctuations in renal function. More recent evidence from controlled studies suggests that the risk is likely nonexistent in patients with normal renal function, but there may be a risk in patients with renal insufficiency. However, even in this patient population, the risk of CI-AKI is probably much smaller than traditionally assumed. Since volume expansion is the only preventive strategy with a convincing evidence base, liberal hydration should be encouraged to further minimize the risk. The benefits of the diagnostic information gained from contrast-enhanced examinations will still need to be balanced with the potential risk of CI-AKI for the individual patient and clinical scenario.

Radiographic contrast-media-induced acute kidney injury: pathophysiology and prophylactic strategies

Contrast-induced acute kidney injury (CI-AKI) is one of the most widely discussed and debated topics in cardiovascular medicine. With increasing number of contrast-media- (CM-) enhanced imaging studies being performed and growing octogenarian population with significant comorbidities, incidence of CI-AKI remains high. In this review, pathophysiology of CI-AKI, its relationship with different types of CM, role of serum and urinary biomarkers for diagnosing CI-AKI, and various prophylactic strategies used for nephroprotection against CI-AKI are discussed in detail.

Volume-to-creatinine clearance ratio in patients undergoing coronary angiography with or without percutaneous coronary intervention: implications of varying definitions of contrast-induced nephropathy

OBJECTIVES

Whether predicting the risk of early serum creatinine rise using the ratio of the volume of contrast media administered to the estimated creatinine clearance (V/CrCl) is applicable to the broader definition of contrast-induced nephropathy (CIN) (≥0.5 mg/dL absolute and/or 25% relative increase from baseline serum creatinine) is unknown.

BACKGROUND

A V/CrCl ≥4 has been proven to predict the risk of ≥0.5 mg/dL postprocedural absolute rise in serum creatinine.

METHODS

A total of 722 patients undergoing coronary angiography ± percutaneous coronary intervention (PCI) between March 2011 and October 2011 with paired serum creatinine determinations at preprocedure and within 72-hr postprocedure were analyzed. The V/CrCl ratio was calculated by dividing the volume of contrast received by the patient's creatinine clearance. CIN using different definitions was termed as CINnarrow (rise in serum creatinine ≥0.5 mg/dL) and CINbroad (rise in serum creatinine ≥0.5 mg/dL and/or ≥25% increase in baseline serum creatinine).

RESULTS

The mean age was 66 ± 11 years and the mean baseline serum creatinine was 1.1 ± 0.8 mg/dL. Patients with V/CrCl ≥4 were significantly older and more frequently underwent ad hoc PCI compared with those with V/CrCl <4. CINnarrow and CINbroad were observed in 13 versus 3% (P < 0.001) and 23 versus 11% (P < 0.001) of patients with or without V/CrCl ≥4, respectively. After statistical adjustment, a V/CrCl ratio ≥4 remained significantly associated with the risk of both CINnarrow [adjusted OR 3.5, 95% confidence intervals (95% CI) 1.7-7.3; P < 0.001] and CINbroad (adjusted OR 2.5, 95% 1.6-3.9; P < 0.001).

CONCLUSIONS

A volume-to-creatinine clearance ratio ≥4 significantly predicts the risk of early postprocedural rise in serum creatinine regardless of the CIN definition adopted.

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.

Contrast-induced nephropathy in interventional cardiology

Development of contrast-induced nephropathy (CIN), ie, a rise in serum creatinine by either ≥0.5 mg/dL or by ≥25% from baseline within the first 2-3 days after contrast administration, is strongly associated with both increased inhospital and late morbidity and mortality after invasive cardiac procedures. The prevention of CIN is critical if long-term outcomes are to be optimized after percutaneous coronary intervention. The prevalence of CIN in patients receiving contrast varies markedly (from <1% to 50%), depending on the presence of well characterized risk factors, the most important of which are baseline chronic renal insufficiency and diabetes mellitus. Other risk factors include advanced age, anemia, left ventricular dysfunction, dehydration, hypotension, renal transplant, low serum albumin, concomitant use of nephrotoxins, and the volume of contrast agent. The pathophysiology of CIN is likely to be multifactorial, including direct cytotoxicity, apoptosis, disturbances in intrarenal hemodynamics, and immune mechanisms. Few strategies have been shown to be effective to prevent CIN beyond hydration, the goal of which is to establish brisk diuresis prior to contrast administration, and to avoid hypotension. New strategies of controlled hydration and diuresis are promising. Studies are mixed on whether prophylactic oral N-acetylcysteine reduces the incidence of CIN, although its use is generally recommended, given its low cost and favorable side effect profile. Agents which have been shown to be ineffective or harmful, or for which data supporting routine use do not exist, include fenoldopam, theophylline, dopamine, calcium channel blockers, prostaglandin E(1), atrial natriuretic peptide, statins, and angiotensin-converting enzyme inhibitors.

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.

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.

Contrast medium-induced nephropathy. Aspects on incidence, consequences, risk factors and prevention

Contrast media-induced nephropathy (CIN) is a well-known complication of radiological examinations employing iodine contrast media (I-CM). The rapid development and frequent use of coronary interventions and multi-channel detector computed tomography with concomitant administration of relatively large doses of I-CM has contributed to an increasing number of CIN cases during the last few years. Reduced renal function, especially when caused by diabetic nephropathy or renal arteriosclerosis, in combination with dehydration, congestive heart failure, hypotension, and administration of nephrotoxic drugs are risk factors for the development of CIN. When CM-based examinations cannot be replaced by other techniques in patients at risk of CIN, focus should be directed towards analysis of number and type of risk factors, adequate estimation of GFR, institution of proper preventive measures including hydration and post-procedural observation combined with surveillance of serum creatinine for 1-3 days. For the radiologist, there are several steps to consider in order to minimise the risk for CIN: use of "low-" or "iso-osmolar" I-CM and dosing the I-CM in relation to GFR and body weight being the most important as well as utilizing radiographic techniques to keep the I-CM dose in gram iodine as low as possible below the numerical value of estimated GFR. There is as yet no pharmacological prevention that has been proven to be effective.

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.