Pre-procedural renal resistive index accurately predicts contrast-induced acute kidney injury in patients with preserved renal function submitted to coronary angiography

Current Insights into the Significance of the Renal Resistive Index in Kidney and Cardiovascular Disease

Initially, the renal resistive index (RRI) was investigated with the aim of improving diagnosis in kidney diseases, but this goal was not met. Recently, many papers have highlighted the prognostic significance of the RRI in chronic kidney disease: specifically, in estimating the revascularization success of renal artery stenoses or the evolution of the graft and the recipients in renal transplantation. Moreover, the RRI has become significant in the prediction of acute kidney injury in critically ill patients. Studies in renal pathology have revealed correlations of this index with parameters of systemic circulation. The theoretical and experimental premises of this connection were then reconsidered, and studies analyzing the link between RRI and arterial stiffness, central and peripheral pressure, and left ventricular flow were conducted with this purpose. Many data currently indicate that RRI is influenced more by pulse pressure and vascular compliance than by renal vascular resistance-assuming that RRI reflects the complex interplay between systemic circulation and renal microcirculation and should be considered a marker of systemic cardiovascular risk beyond its prognostic relevance for kidney disease. In this review, we overview the clinical research that reveals the implications of RRI in renal and cardiovascular disease.

Repeated Dose of Contrast Media and the Risk of Contrast-Induced Acute Kidney Injury in a Broad Population of Patients Hospitalized in Cardiology Department

Contrast-induced acute kidney injury (CI-AKI) can lead to the development of chronic kidney disease (CKD) and impaired in-hospital and long-term outcomes among cardiac patients. The aim of this study was to evaluate the impact of repeated contrast media (CM) administration during a single hospitalization on the rate of CI-AKI. The study group (n = 138) comprised patients with different diagnoses who received CM more than once during hospitalization, while the control group (n = 153) involved CAD patients subject to a single CM dose. Following propensity score matching (PSM), both groups of n = 84 were evenly matched in terms of major baseline variables. CI-AKI was defined by an absolute increase in SCr ≥ 0.3 mg/dL or >50% relative to the baseline value within 48–72 h from the last CM dose. Patients in the study group were older, had a higher prevalence of diabetes and CKD, received a higher total volume of CM, had a lower left ventricular ejection fraction, lower prevalence of multivessel coronary artery disease (MV-CAD), and a trend towards a lower prevalence of arterial hypertension and smoking. SCr did not differ between the study and control groups at 72 h after the CM use. CI-AKI occurred in 18 patients in the study (13.0%) and in 18 patients (11.8%) in the control group (p = 0.741). The rate of CI-AKI was also comparable following the PSM (13.1% vs. 13.1%, p = 1.0). Logistic regression analysis revealed that CKD, diabetes mellitus, MV-CAD, age, and non-steroidal anti-inflammatory drugs use, but not repeated CM use, were independent predictors of CI-AKI.

Contrast-induced nephropathy in non-cardiac vascular procedures, a narrative review: Part 2

This is Part 2 of a narrative review summarizing the literature on CIN after non-cardiac vascular diagnostic or therapeutic procedures, focusing on peripheral artery disease (PAD) and renal artery stenosis (RAS). Part 1 discussed CIN in relation to aortic aneurysms and carotid stenosis. We comment on the incidence, biomarkers, risk factors, and consequences of CIN in patients with PAD or RAS, as well as on strategies to prevent CIN. Future perspectives in the field of CIN in relation to non-cardiac vascular procedures are also considered.

Doppler-derived renal resistive index helps predict acute kidney injury in patients undergoing living-related liver transplantation

BACKGROUND

Acute kidney injury (AKI) is commonly associated with increased postoperative morbidity in liver transplant (LT) recipients. The aim of this study was to identify the role of renal resistive index (RRI) in predicting AKI and to study the factors associated with AKI in LT recipients.

PATIENTS AND METHODS

We performed a single-center, prospective study, including adult living donor LT recipients at our center between January 2018 and September 2019 with no preoperative renal dysfunction. RRI was calculated on ultrasound doppler once preoperatively, and once daily in the postoperative period through postoperative day (POD) six. Patients were grouped into AKI and non-AKI groups for comparison.

RESULTS

Fifty patients were included in the study (mean age, 44 years; 20% females). AKI developed in 25 patients (50%). Both groups were similar in baseline characteristics. RRI of ≥ 0.69 on POD 2 predicted AKI (sensitivity 88%; specificity 92%). RRI on the day before AKI diagnosis (0.71 vs. 0.65) and on the day of diagnosis (0.72 vs. 0.65) were significantly increased relative to preoperative baseline.

CONCLUSIONS

Doppler-derived RRI is a rapid, non-invasive, and bedside procedure capable of predicting the occurrence of postoperative AKI in LT recipients.

High-sensitive cardiac troponin for the diagnosis of acute myocardial infarction in different chronic kidney disease stages

BACKGROUND

Chronic kidney disease (CKD) are associated with acute myocardial infarction (AMI). High-sensitive cardiac troponin (hs-cTn) has been evidenced to enhance the early diagnostic accuracy of AMI, but hs-cTn levels are often chronically elevated in CKD patients, which reduces their diagnostic utility. The aim of this study was to derive optimal cutoff-values of hs-cTn levels in patients with CKD and suspected AMI.

METHODS

In this retrospective paper, a total of 3295 patients with chest pain (2758 in AMI group and 537 in Non-AMI group) were recruited, of whom 23.1% were had an estimated glomerular filtration rate (eGFR) of < 60 mL min-1 (1.73 m2)-1. Hs-cTnI values were measured at presentation.

RESULTS

AMI was diagnosed in 83.7% of all patients. The optimal value of hs-TnI in diagnosing AMI was 1.15 ng mL-1, which were higher in males than females comparing different cutoff-values of subgroups divided by age, gender and renal function, and which increased monotonically with decreasing of eGFR because in patients with CKD without AMI, the correlation between hs-cTnI and renal function is low but significant (r2 = 0.067, P < 0.001).

CONCLUSIONS

Different optimal cutoff-values of hs-cTnI in the diagnosis of AMI in patients with CKD were helpful to the clinical diagnosis of AMI in various populations and were higher in males than females, but which was needed to be validated by multicenter randomized controlled clinical studies in the future.

Correlation between Kidney Function and Sonographic Texture Features after Allograft Transplantation with Corresponding to Serum Creatinine: A Long Term Follow-Up Study

Background:

The ability to monitor kidney function after transplantation is one of the major factors to improve care of patients.

Objective:

Authors recommend a computerized texture analysis using run-length matrix features for detection of changes in kidney tissue after allograft in ultrasound imaging.

Material and Methods:

A total of 40 kidney allograft recipients (28 male, 12 female) were used in this longitudinal study. Of the 40 patients, 23 and 17 patients showed increased serum creatinine (sCr) (increased group) and decreased sCr (decreased group), respectively. Twenty run-length matrix features were used for texture analysis in three normalizations. Correlations of texture features with serum creatinine (sCr) level and differences between before and after follow-up for each group were analyzed. An area under the receiver operating characteristic curve (Az) was measured to evaluate potential of proposed method.

Results:

The features under default and 3sigma normalization schemes via linear discriminant analysis (LDA) showed high performance in classifying decreased group with an A_z of 1. In classification of the increased group, the best performance gains were determined in the 3sigma normalization schemes via LDA with an A_z of 0.974 corresponding to 95.65% sensitivity, 91.30% specificity, 93.47% accuracy, 91.67% PPV, and 95.45% NPV.

Conclusion:

Run-length matrix features not only have high potential for characterization but also can help physicians to diagnose kidney failure after transplantation.

Renal resistive index and long-term outcome in patients with coronary artery disease

Background

The study aimed to evaluate the application of intra-renal Doppler flow indices for the prediction of major adverse cardiac and cerebrovascular events (MACCE) during 24-month follow-up in patients with coronary artery disease (CAD) subject to coronary angiography (CA).

Methods

This prospective study comprised 111 consecutive patients with stable and unstable CAD (68.5% men; median age 65 years), referred for CA. Ultrasonographic parameters of intra-renal blood flow in arcuate/interlobular arteries, including renal resistive index (RRI) and pulsatility index (RPI), were acquired directly before and 1 h after the procedure. Endpoint of MACCE (cardiovascular death, myocardial infarction, myocardial revascularization or stroke) were recorded during 24-month follow-up.

Results

MACCE occurred in 14 patients (12.6%). Patients with MACCE had more diffuse CAD reflected by Syntax score (23.6 vs.14.4 pts., p = 0.02), higher platelet level (242.4 vs. 207.2 × 1000/μl, p = 0.01), higher rate of left main CAD (42.9% vs.5.2%, p < 0.001) and left ventricular ejection fraction < 50% (50% vs.23.7%,p = 0.045). Patients with MACCE had higher pre-procedural (0.68 ± 0.06 vs. 0.62 ± 0.06, p < 0.001) and post-procedural RRI (0.72 ± 0.06 vs.0.66 ± 0.06, p = 0.01), but comparable RPI (p = 0.63 and p = 0.36, respectively). Cox proportional hazards model revealed that pre-procedural RRI (OR = 1.11 per 0.01; p = 0.02) and left main CAD (OR = 5.75, p = 0.002) were the only independent predictors of MACCE occurrence. Receiver operator characteristic curve analysis revealed that preprocedural RRI > 0.645 accurately predicted the composite endpoint (AUC = 0.78, p = 0.001) and identified patients with impaired 24-month prognosis according to Kaplan-Meier curve (log-rank p < 0.001).

Conclusions

Increased pre-procedural RRI, together with left main CAD, are associated with worse 24-month prognosis in patients with CAD referred for CA.

Bedside Renal Doppler Ultrasonography and Acute Kidney Injury after TAVR

Acute kidney injury (AKI) following transcatheter aortic valve replacement (TAVR) is associated with a dismal prognosis. Elevated renal resistive index (RRI), through renal Doppler ultrasound (RDU) evaluation, has been associated with AKI development and increased systemic arterial stiffness. Our pilot study aimed to investigate the performance of Doppler based RRI to predict AKI and outcomes in TAVR patients. From May 2018 to May 2019, 100 patients with severe aortic stenosis were prospectively enrolled for TAVR and concomitant RDU evaluation at our institution (Nouvel Hôpital Civil, Strasbourg University, France). AKI by serum Creatinine (sCr-AKI) was defined according to the VARC-2 definition and AKI by serum Cystatin C (sCyC-AKI) was defined as an sCyC increase of greater than 15% with baseline value. Concomitant RRI measurements as well as renal and systemic hemodynamic parameters were recorded before, one day, and three days after TAVR. It was found that 10% of patients presented with AKI_sCr and AKI_sCyC. The whole cohort showed higher baseline RRI values (0.76 ± 0.7) compared to normal known and accepted values. AKI_sCyC had significant higher post-procedural RRI one day (Day 1) after TAVR (0.83 ± 0.1 vs. 0.77 ± 0.6, CI 95%, p = 0.005). AUC for AKI_sCyC was 0.766 and a RRI cut-off value of ≥ 0.795 had the most optimal sensitivity/specificity (80/62%) combination. By univariate Cox analysis, Mehran Risk Score, higher baseline right atrial pressure at baseline > 0.8 RRI values one day after TAVR (HR 6.5 (95% CI 1.3-32.9; p = 0.021) but not RRI at baseline were significant predictors of AKI_sCyC. Importantly, no significant impact of baseline biological parameters, renal or systemic parameters could be demonstrated. Doppler-based RRI can be helpful for the non-invasive assessment of AKI development after TAVR.

Is High Preprocedural Renal Resistive Index Sensitive Enough to Predict Iodine Contrast-Induced Nephropathy in Patients Receiving Intra-Arterial Iodinate Contrast?

PURPOSE

Renal Resistive Index (RRI) is a newly introduced sonographic index in predicting contrast-induced nephropathy (CIN) development. It has been suggested that RRI > 0.69 should be considered as a risk factor for CIN development. The present study aimed to calculate the predictive value of RRI using a cutoff point of 0.69.

METHODS

A total of 90 patients who were a candidate for coronary vessels angiography were enrolled in this study. Color Doppler ultrasonography was performed and RRI was measured. Patients were followed up for 48 hours after contrast media exposure for the CIN development. The diagnosis of CIN was based on a 25% relative rise or 0.5 mg/dL absolute rise in creatinine level. The predictive values of RRI were measured using 0.69 as a cutoff point.

RESULTS

Out of 90 patients, CIN developed in 3 patients and 17 patients had preprocedural RRI > 0.69. Of 3 patients with CIN, 1 had RRI > 0.69. Using 0.69 as the cutoff point, the measured sensitivity and specificity of RRI were 33.3% and 83.9%, respectively.

CONCLUSIONS

RRI > 0.69 is not a sensitive index in predicting the CIN development and cannot be used as an independent factor.

Increased circulating galectin-1 levels are associated with the progression of kidney function decline in patients undergoing coronary angiography

Galectin-1 modulates acute and chronic inflammation, and is associated with glucose homeostasis and chronic renal disease. Whether the serum galectin-1 level can predict short-term and long-term renal outcomes after contrast exposure in patients undergoing coronary angiography (CAG) remains uncertain. This study aimed to evaluate the relationship between the serum galectin-1 level and the incidence of contrast-induced nephropathy (CIN), and to investigate the predictive role of the circulating galectin-1 level for renal function decline in patients undergoing CAG. In total, 798 patients who had undergone CAG were enrolled. Baseline creatinine and serum galectin-1 levels were determined before CAG. CIN was defined as an increase in the serum creatinine level of 0.5 mg/dl or a 25% increase from baseline within 48 h after the procedure, and renal function decline was defined as > 30% reduction of the estimated glomerular filtration rate from baseline. All patients were followed for at least 1 year or until the occurrence of death after CAG. Overall, CIN occurred in 41 (5.1%) patients. During a median follow-up period of 1.4 ± 1.1 years, 80 (10.0%) cases showed subsequent renal function decline. After adjustment for demographic characteristics, kidney function, traditional risk factors, and medications, higher galectin-1 levels were found to be associated independently with a greater risk of renal function decline [tertile 2: hazard ratio (HR) 5.56, 95% confidence interval (CI) 1.79-17.22; tertile 3: HR 5.56, 95% CI 1.97-16.32], but not with CIN, regardless of the presence of diabetes. In conclusion, higher baseline serum galectin-1 levels were associated with a greater risk of renal function decline in patients undergoing CAG, but were not associated independently with CIN.

Prediction Efficiency of Postoperative Acute Kidney Injury in Acute Stanford Type A Aortic Dissection Patients with Renal Resistive Index and Semiquantitative Color Doppler

Objectives

This study is aimed to evaluate the efficiency in early prediction of postoperative persistent acute kidney injury (PAKI) after surgery in acute Stanford type A aortic dissection (AAAD) patients by using Doppler renal resistive index (RRI) and semiquantitative color (SQC) Doppler grade, respectively.

Methods

84 AAAD patients received Sun's surgical management, and 67 patients were enrolled. RRI and SQC Doppler grade were evaluated by ultrasonography, respectively, at 6 hours after surgery. Serum creatinine (sCr) was recorded before operation and at 24 hours, 48 hours, and 72 hours after operation. AKI grade was evaluated according to the classifications of the Acute Kidney Injury Network (AKIN). PAKI is defined as persistent oliguria and/or sCr elevation after 3 days. RRI and SQC Doppler grade were compared, respectively, between the PAKI and non-PAKI groups. Potential predictors were first tested by univariate logistic regression analysis, and a multivariate model was identified to determine the independent predictive ability of RRI and SQC Doppler grade for the PAKI. Receiver operating characteristic (ROC) analysis was performed to compare the diagnostic accuracy between RRI and SQC Doppler grade in early prediction of PAKI by using AKIN classifications as the reference standard.

Results

Of a total of 67 patients enrolled during the study period, 21 (31.3%) patients suffered from PAKI and 8 (11.9%) patients required dialysis. There are significant differences in RRI (0.80 ± 0.09 vs. 0.70 ± 0.05, P=0.002) and SQC Doppler grade (x²=12.193, P=0.007) between the 2 groups with and without PAKI. Univariate analysis showed that RRI, SQC Doppler grade, length of stay in ICU, time of CPB, and length of stay in hospital were significant predictors of PAKI. RRI and the SQC Doppler grade remained independent predictors of PAKI. Area under the curve (AUC) of RRI was 0.855 (95% CI, 0.74–0.96) with cutoff value 0.725 (sensitivity 90.9% and specificity 71.1%), AUC of SQC Doppler grade was 0.642 (95% CI, 0.49–0.79) with cutoff value grade 2 (sensitivity 50% and specificity 73.3%).

Conclusion

Both postoperative RRI and SQC Doppler grade are independent predictors for PAKI after surgery in AAAD patients. Both postoperative RRI and SQC Doppler grade can be obtained rapidly by bedside ultrasound, which is a good tool for early prediction for postoperative PAKI.

Increased renal cortical stiffness obtained by share-wave elastography imaging significantly predicts the contrast-induced nephropathy in patients with preserved renal function

PURPOSE

We aimed to investigate the relation between renal cortical stiffness (CS) obtained by shear-wave elastography (SWE) and contrast-induced nephropathy (CIN) development in interventional treatment-planned acute coronary syndrome (ACS) patients.

METHODS

Our study group consisted of 465 ACS patients. Routine laboratory assessments, B-mode, Doppler, and SWE renal ultrasonography (USG) evaluations were performed. Renal resistive index (RRI), renal pulsatility index (RPI), and acceleration time (AT) and CS were measured. Patients were grouped as with and without CIN.

RESULTS

Among the study group, 55 patients (11.8%) had CIN. Age, diabetes mellitus (DM), hypertension (HT), basal creatinine, CK-MB and troponin I levels, contrast volume, contrast volume/weight ratio, SYNTAX score, RRI, RPI, AT, and CS values were significantly higher in patients with CIN. eGFR was lower in patients who developed CIN. Age, contrast volume/weight ratio, and CS were determined as independent predictors of CIN occurrence in logistic regression analysis. In multivariate logistic analysis, increase of age (each year), contrast volume/weight (each 0.2 mL/kg), and CS (each 1 kPa) were found to augment the development of CIN by 7.1, 59.5, and 62.3%, respectively. In the ROC analysis, CS had the highest AUROC value. The cutoff value of CS obtained by the ROC curve analysis was 7 kPa for the CIN development (sensitivity: 74.5%, specificity: 72.5%).

CONCLUSION

CS value is a simple, cheap, reproducible, noninvasive, and objective parameter for the detection of CIN development. ACS patients should be directed to renal USG, and routine CS value should be written besides USG measurements in reports.

The predictive value of the renal resistive index for contrast-induced nephropathy in patients with acute coronary syndrome

Background

Percutaneous coronary intervention (PCI) has been associated with contrast-induced nephropathy (CIN) at a rate that varies depending on the patient’s risk factors. This study was conducted to evaluate the predictive value of the renal resistive index (RRI) for CIN in patients with acute coronary syndrome (ACS) undergoing PCI.

Methods

This prospective study enrolled 146 consecutive patients with ACS. Renal Doppler ultrasound examinations to measure RRI were performed pre-PCI and at 1 h and 24 h after PCI. The primary endpoint was CIN, defined as a relative (≥25%) or absolute (≥0.5 mg/dL; 44 μmol/L) increase in serum creatinine from baseline within 48 h after contrast exposure.

Results

CIN was identified in 31 patients (21.2%); however, none of the patients required haemodialysis. Compared to patients without CIN, higher RRIs were observed at 1 h (0.71 ± 0.05 vs. 0.65 ± 0.06, p < 0.05) and 24 h (0.70 ± 0.05 vs. 0.66 ± 0.06, p < 0.05) post-procedure in patients with CIN. The RRI rose transiently from baseline (0.68 ± 0.05) to 1 h (0.71 ± 0.05) and then tended to decline at 24 h (0.70 ± 0.05). A receiver operating characteristic curve analysis showed that the pre-procedure RRI was a powerful predictive indicator of CIN (area under the curve = 0.661, p = 0.006). The best cutoff value was 0.69 with 67.7% sensitivity and 67% specificity. Besides hyperuricemia and chronic kidney disease, the multivariate logistic regression analysis revealed that a high baseline RRI (≥0.69) was a significant predictor of CIN (odds ratio = 4.445; 95% confidence interval: 1.806–10.937; p = 0.001).

Conclusions

A high pre-procedural RRI appears to be independently predictive of CIN in patients with ACS undergoing PCI.

Renal intraparenchymal resistive index: the ultrasonographic answer to many clinical questions

The use of renal resistive indices (RRIs) for the study of renal microcirculation has in the past been proposed for the identification of renal organ damage or even to specifically identify injury to some areas of the renal parenchyma. Nevertheless, according to the most recent evidences from literature this organ-based conception of RRIs has been proven to be partial and unable to explain the RRIs variations in clinical settings of sepsis or combined organ failure of primitively extrarenal origin or, more generally, the deep connection between RRIs and hemodynamic factors such as compliance and pulsatility of the large vessels. The aim of this review is to explain the physiopathological basis of RRIs determination and the most common interpretative errors in their analysis. Moreover, through a comprehensive vision of these Doppler indices, the traditional and emerging clinical application fields for RRIs are discussed.

Renal resistive index as an early predictor and discriminator of acute kidney injury in critically ill patients; A prospective observational cohort study

Background

Acute kidney injury (AKI) complicates shock. Diagnosis is based on rising creatinine, a late phenomenon. Intrarenal vasoconstriction occurs earlier. Measuring flow resistance in the renal circulation, Renal Resistive Index (RRI), could become part of vital organ function assessment using Doppler ultrasound. Our aim was to determine whether RRI on ICU admission is an early predictor and discriminator of AKI developed within the first week.

Methods

In this prospective cohort of mixed ICU patients with and without shock, RRI was measured <24-h of admission. Besides routine variables, sublingual microcirculation and bioelectrical impedance were measured. AKI was defined by the Kidney Disease Improving Global Outcomes criteria. Uni- and multivariate regression and Receiver Operating Characteristics curve analyses were performed.

Results

Ninety-nine patients were included, median age 67 years (IQR 59–75), APACHE III score 67 (IQR 53–89). Forty-nine patients (49%) developed AKI within the first week. AKI patients had a higher RRI on admission than those without: 0.71 (0.69–0.73) vs. 0.65 (0.63–0.68), p = 0.001. The difference was significant for AKI stage 2: RRI = 0.72 (0.65–0.80) and 3: RRI = 0.74 (0.67–0.81), but not for AKI stage 1: RRI = 0.67 (0.61–0.74). On univariate analysis, RRI significantly predicted AKI 2–3: OR 1.012 (1.006–1.019); Area Under the Curve (AUC) of RRI for AKI 2–3 was 0.72 (0.61–0.83), optimal cut-off 0.74, sensitivity 53% and specificity 87%. On multivariate analysis, RRI remained significant, independent of APACHE III and fluid balance; adjusted OR: 1.008 (1.000–1.016).

Conclusions

High RRI on ICU admission was a significant predictor for development of AKI stage 2–3 during the first week. High RRI can be used as an early warning signal RRI, because of its high specificity. A combined score including RRI, APACHE III and fluid balance improved AKI prediction, suggesting that vasoconstriction or poor vascular compliance, severity of disease and positive fluid balance independently contribute to AKI development.

Trial registration

ClinicalTrials.gov NCT02558166.