Validating the use of contrast-induced nephropathy prediction models in endovascular aneurysm repairs

Contrast-Free Endovascular Aneurysm Repair Combined With Fibrin Sealant Filling for Treating Abdominal Aortic Aneurysm: Technical Note

INTRODUCTION

Endovascular aneurysm repair using iodinated contrast agents risks contrast-induced nephropathy, especially in high-risk patients. This technical note describes a contrast-free endovascular aneurysm repair (EVAR) protocol using preoperative imaging measurement and fibrin sealant (FS) filling.

TECHNIQUE

Preoperative imaging measurement and intraoperative guidewire manipulation facilitated anatomical identification without contrast. After endograft deployment, the aneurysm sac was filled with FS if endoleak was indicated by pressure fluctuations.

RESULT

Between 2017 and 2020, 6 high-risk patients underwent contrast-free EVAR with FS filling. Complete exclusion was achieved in all cases. Over follow-up, no endoleaks, deterioration in renal function, or other complications were observed.

CONCLUSION

Contrast-free EVAR with FS filling shows early feasibility as an alternative technique for contrast-induced nephropathy (CIN) high-risk patients, while larger studies with long-term monitoring are imperative to validate outcomes.

CLINICAL IMPACT

This study showcases a contrast-free EVAR technique with fibrin sealant filling for high-risk CIN patients. It offers a safer approach for those with renal challenges, reducing CIN risk. The technique's feasibility in a small cohort suggests its utility in treating AAA without iodinated contrast, crucial for patients with specific health risks. For clinicians, it introduces a method that decreases nephrotoxic risks, potentially changing practice for vulnerable patients.

Intravascular Ultrasound Versus Computed Tomography Angiography in Sizing and Operative Management of Endovascular Aortic Aneurysm Repair

OBJECTIVES

An abdominal aortic aneurysm (AAA) is a potentially life-threatening condition, the management of which has dramatically evolved over the past 2 decades with an increasing tendency toward endovascular repair (EVAR) rather than open surgical repair. Classically, contrast-enhanced multislice computed tomography (CT) angiography (CTA) is performed preoperatively for procedure sizing and EVAR planning. This entails voluminous contrast injection with risk of allergic reaction, nephropathy, and radiation exposure. Intra-vascular ultrasound (IVUS) has been increasingly used to guide EVAR procedures intraoperatively. The aim of this study is to investigate the accuracy of IVUS in sizing AAAs, device selection, and EVAR planning compared to the gold standard CTA.

DESIGN

This is a prospective observational study enrolling 10 patients who underwent standard infrarenal EVAR procedures performed for unruptured infrarenal AAAs over the course of 1 year. All patients had a preoperative CTA done upon which aneurysm sizing and device planning were performed, and the measurements obtained were compared to those obtained from intraoperative IVUS.

METHODS

All participating patients had unruptured infrarenal AAA, had no renal impairment, and had anatomical suitability for EVAR according to the instructions for use (IFU) of the device manufacturer. Primary endpoint was comparing anatomical measurements recorded by IVUS with those obtained from the preoperative CTA.

RESULTS

Mean age was 65.6 (±6.19), all patients were males and hypertensives and 4 (40%) had a positive family history for AAA. On comparing mean measurements taken by CTA and IVUS, there was no statistically significant differences with exception of maximal aortic diameter and aortic diameter at site of bifurcation (both p-values <.001). There were no statistically significant differences in length measurements between the 2 imaging modalities. Computed tomography angiography was more associated with neck thrombus detection, and IVUS was more associated with calcification detection.

CONCLUSION

Although CT angiography is still the gold standard imaging modality for AAA, IVUS use is very beneficial in EVAR sizing and planning, in addition to intra-operative guidance of the procedure, saving the patient significant time, contrast administration, and radiation exposure, especially in patients with renal impairment and contrast allergy.

CLINICAL IMPACT

A preoperative CT angiogram is the gold standard required investigation for planning and sizing EVARs, with subsequent contrast injection entailing a risk of contrast induced nephropathy and allergic reactions. IVUS has been used as an adjuvant technique to guide EVAR stent graft deployment. However, our study concluded that it can also be reliably used in sizing and planning of the EVAR stent graft along with complementary non contrast imaging, especially in patients with high risk for contrast induced nephropathy and contrast allergy.

A novel pre-operative risk assessment tool to identify patients at risk of contrast associated acute kidney injury after endovascular abdominal aortic aneurysm repair

OBJECTIVES

Contrast-associated acute kidney injury (CA-AKI) after endovascular abdominal aortic aneurysm repair (EVAR) is associated with mortality and morbidity. Risk stratification remains a vital component of preoperative evaluation. We sought to generate and validate a pre-procedure CA-AKI risk stratification tool for elective EVAR patients.

METHODS

We queried the Blue Cross Blue Shield of Michigan Cardiovascular Consortium (BMC2) database for elective EVAR patients and excluded those on dialysis, with a history of renal transplant, death during procedure, and without creatinine measures. Association with CA-AKI (rise in creatinine > 0.5 mg/dL) was tested using mixed effects logistic regression. Variables associated with CA-AKI were used to generate a predictive model via a single classification tree. The variables selected by the classification tree were then validated by fitting a mixed effects logistic regression model into the Vascular Quality Initiative (VQI) dataset.

RESULTS

Our derivation cohort included 7,043 patients, 3.5% of whom developed CA-AKI. After multivariate analysis, age (OR 1.021, 95% CI 1.004-1.040), female sex (OR 1.393, CI 1.012-1.916), GFR < 30 ml/min (OR 5.068, CI 3.255-7.891), current smoking (OR 1.942, CI 1.067-3.535), COPD (OR 1.402, CI 1.066-1.843), maximum AAA diameter (OR 1.018, CI 1.006-1.029), and presence of iliac artery aneurysm (OR 1.352, CI 1.007-1.816) were associated with increased odds of CA-AKI. Our risk prediction calculator demonstrated that patients with a GFR <30 ml/min, females, and patients with a maximum AAA diameter of > 6.9 cm are at higher risk of CA-AKI after EVAR. Using the VQI dataset (N = 62,986), we found that GFR <30 ml/min (OR 4.668, CI 4.007-5.85), female sex (OR 1.352, CI 1.213-1.507), and maximum AAA diameter > 6.9 cm (OR 1.824, CI 1.212-1.506) were associated with increased risk of CA-AKI after EVAR.

CONCLUSIONS

Herein, we present a simple and novel risk assessment tool that can be used pre-operatively to identify patients at risk of CA-AKI after EVAR. Patients with a GFR < 30 ml/min, maximum AAA diameter > 6.9 cm, and females who are undergoing EVAR may be at risk for CA-AKI after EVAR. Prospective studies are needed to determine the efficacy of our model.

The acute impact of baseline renal function and contrast medium volume/estimated glomerular filtration rate ratio on reduced renal function following endovascular abdominal aortic aneurysm repair

OBJECTIVE

The aim of this study was to determine the acute impact of baseline serum creatinine, estimated glomerular filtration rate (eGFR), and contrast medium volume (CMV) on the incidence of reduced renal function (RRF) after endovascular abdominal aortic aneurysm repair (EVAR). We aimed to determine if the CMV/eGFR ratio was a predictor of RRF.

METHODS

This study is a retrospective review of EVAR patients in the Society for Vascular Surgery/Vascular Quality Initiative (SVS/VQI) from January 2015 to August 2020. Reduced renal function was defined as > 0.3 mg/dl (26.5 μmol/L), 50% increase from baseline, and temporary or permanent dialysis. Receiver operator characteristic (ROC) curve analyses were conducted for serum creatinine, eGFR, contrast volume, fluid volume, and CMV/eGFR ratio. Two data sets (training and test) were developed followed by multivariate analyses.

RESULTS

SVS/VQI data for EVAR contained 38,701 records, of which 30,539 were divided into training (n = 18,283; 60%) and test (n = 12,256; 40%) data sets. RRF rate for the training set was 3.6% (n = 667) and 3.4% (n = 420) for the test data. RRF patients included more females (29.4 vs 19.0%, p < 0.001), were older in age (75.6 + 8.4 vs 73.3 + 8.7 years), had more congestive heart failure (22.3 vs 12.2%, p < 0.001), and more COPD (42.0 vs 34.2%, p < 0.001). An ROC analysis revealed that eGRF, creatinine, contrast, intravenous fluid, and contrast medium volume (CMV)/eGFR ratio were all significantly (p < 0.05) correlated with RRF. The eGFR and CMV/eGFR ratio had the largest area under the curve, (0.26) and (0.65), respectively, while fluid had the lowest (0.54). Negative predictive values were 93.7 (CMV/eGFR), 93.9 (creatinine), 94.2 (eGFR), 92.8 (contrast), and 92.6 (intravenous fluid). Multivariate analysis of the training data set resulted in the CMV/eGFR ratio as an independent predictor of RRF (odds ratio, OR: 1.9 with 95% CI: 1.6, 2.2, p < 0.015). For the test data, the CMV/eGFR ratio was an independent predictor of RRF (OR: 1.8, CI: 1.4 to 2.2, p < 0.001) as well as several other variables.

CONCLUSION

RRF after EVAR is a dreaded and potentially devastating complication. Baseline serum creatinine, eGFR, contrast medium volume, and the ratio (CMV/eGFR) were all significantly associated with RRF. The optimal cut-off value for the CMV/eGFR ratio, ≤ 2, provides an easy-to-use equation to provide a suggested contrast target based on initial renal function with caution applied for high-risk patients.

Monoplane versus biplane fluoroscopy in patients undergoing fenestrated/branched endovascular aortic repair

OBJECTIVE

Endovascular aortic repair (EVAR) with fenestrated (F-EVAR) or branched (B-EVAR) endografts represents an indispensable tool of modern patient care in vascular surgery. The purpose of this retrospective study was to evaluate the center's initial experience of F/B-EVAR procedures performed under biplane angiography guidance compared with a historical control group.

METHODS

From January 2020 to March 2022, 80 consecutive patients underwent F/B-EVAR under general anesthesia at a single institution. As from January 2021, the deployment of complex stent grafts was performed using an alternative intraoperative imaging modality-a biplane fluoroscopy and angiography. The cohort was divided into monoplane (MPA) and biplane (BPA) groups according to the imaging modality applied. The end points were operation time, fluoroscopy time, radiation exposure, dose of contrast agent, and technical success.

RESULTS

The MPA group included 59 patients (78% male; median age; 74 years; interquartile range [IQR], 66-78 years) and the BPA group 21 patients (85.7% males; median age, 75 years; IQR, 69-79 years). Operation time (median, 320 minutes; IQR, 266-376 minutes) versus (median, 275 minutes; IQR, 216-333 minutes) was significantly lower in the BPA group (P = .006). The median fluoroscopy time (median, 82 minutes; IQR, 57-110 minutes vs median, 68 minutes; IQR, 54-92 minutes), contrast agent volume applied (median, 220 mL; IQR, 179-250 mL vs median, 200 mL; IQR, 170-250 mL), and radiation dose (dose-area product, median, 413 Gy × cm²; IQR, 249-736 Gy × cm²; vs median, 542 Gy × cm²; IQR, 196-789 Gy × cm²) were similar in both groups. Technical success of 96.6% (57/59 cases) versus 100% (21/21 cases) could be achieved in MPA and BPA group, respectively.

CONCLUSIONS

F/B-EVAR procedures performed under BPA guidance were associated with a significant decrease in operation time.

Acute Kidney Injury Risk and Contrast Volume in Intact Versus Ruptured Endovascular Aneurysm Repair in the Vascular Quality Initiative

Objective

Renal impairment after repair of ruptured abdominal aortic aneurysm has been associated with post-operative mortality. Acute kidney injury (AKI) risk specifically related to contrast administration in endovascular aneurysm repair (EVAR) for intact vs ruptured aneurysms has not been previously described. It was our objective to evaluate the risk of AKI and the association with contrast administration in EVAR for ruptured (rEVAR) and intact (iEVAR) aneurysm repair in the Vascular Quality Initiative (VQI).

Methods

Adult patients less than 90 years old undergoing EVAR in the VQI without prior abdominal aortic surgery or who were not actively on dialysis preoperatively were included. Patients immediately converted to an open repair were excluded. Patients were grouped by repair urgency, and patient and operative characteristics and outcomes compared. Univariable and multivariable analyses were performed to identify factors associated with the primary outcome of AKI. Survival was evaluated by Kaplan-Meier analysis.

Results

Of 38,775 EVAR patients identified, 86.5% underwent elective surgery for an intact aneurysm, 8.4% had urgent surgery for a symptomatic, intact aneurysm, and 5.1% had emergent repair for a ruptured aneurysm. Significant risk factors for AKI included contrast volume, a preoperative eGFR <30 mL/min, procedure urgency, COPD, congestive heart failure (CHF), and total procedure time. The factor most associated with AKI was aneurysm rupture prior to repair (OR 8.6, CI 7.2-10.3, P <.01). The association of contrast volume with the outcome was the least strong with a 4% increase in risk per 25 mL of contrast (OR 1.04, 95% CI 1.01-1.07). With the development of AKI, postoperative survival was reduced regardless of indication.

Conclusions

Of all factors assessed, aneurysm rupture was the most and contrast volume the least associated with AKI after EVAR. Further studies should evaluate methods of preventing post-EVAR AKI.

Incidence of Contrast-Induced Nephropathy and Post-Operative Outcomes in Patients Undergoing Chimney Endovascular Aortic Aneurysm Repair

Chimney endovascular aortic aneurysm repair (ch-EVAR) has become a valid alternative to treat complex aneurysms but the occurrence of contrast-induced kidney injury (CI-AKI) is poorly known. This study investigated the incidence and the impact of CI-AKI on post-operative outcomes after ch-EVAR. Consecutive patients who underwent ch-EVAR between July 2010 and 2021 were retrospectively included. CI-AKI was defined based on plasma creatinine levels within 7 days after the intervention according to the "Kidney Disease Improving Global Outcomes" (KDIGO) classification. Among 102 patients included, CI-AKI occurred in 14 cases (13.7%). The 30-day post-operative mortality and complications were significantly higher in patients who developed CI-AKI compared with those who did not (50 vs 9.1%, P = .001 and 57.1 vs 20.5%, P = .007). Over a median follow-up of 24 months (3-39), overall mortality was also significantly higher (78.6 vs 33.0%, P = .002). The pre-operative platelet-to-lymphocyte ratio (PLR) was significantly higher in patients who developed CI-AKI (224.5 vs 147.6, P = .008). CI-AKI is frequent after ch-EVAR and is associated with worse post-operative outcomes. This should increase awareness of clinicians to optimize preventive and therapeutic strategies.

Diseases of the Aorta and Kidney Disease: Conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference

Chronic kidney disease (CKD) is an independent risk factor for the development of abdominal aortic aneurysm (AAA), as well as for cardiovascular and renal events and all-cause mortality following surgery for AAA or thoracic aortic dissection. In addition, the incidence of acute kidney injury (AKI) after any aortic surgery is particularly high, and this AKI per se is independently associated with future cardiovascular events and mortality. On the other hand, both development of AKI after surgery and the long-term evolution of kidney function differ significantly depending on the type of AAA intervention (open surgery vs. the various subtypes of endovascular repair). Current knowledge regarding AAA in the general population may not be always applicable to CKD patients, as they have a high prevalence of co-morbid conditions and an elevated risk for periprocedural complications. This summary of a Kidney Disease: Improving Global Outcomes Controversies Conference group discussion reviews the epidemiology, pathophysiology, diagnosis, and treatment of Diseases of the Aorta in CKD and identifies knowledge gaps, areas of controversy, and priorities for future research.

Contrast-induced nephropathy in non-cardiac vascular procedures, a narrative review: Part 1

Contrast-induced nephropathy (CIN) is an important complication of iodinated contrast medium (CM) administration, which is associated with both short- and long-term adverse outcomes (e.g., cardiorenal events, longer hospital stay, and mortality). CIN has been mainly studied in relation to cardiac procedures, but it can also occur following non-cardiac vascular interventions. This is Part 1 of a narrative review summarizing the available literature on CIN after non-cardiac vascular diagnostic or therapeutic procedures for aortic aneurysm and carotid stenosis. We discuss the definition, pathophysiology, incidence, risk factors, biomarkers, and consequences of CIN in these settings, as well as preventive strategies and alternatives to limit iodinated CM use. Physicians and vascular surgeons should be aware of CM-related adverse events and the potential strategies to avoid them. Clearly, more research in this important field is required.

Renal function-adjusted contrast medium volume is a major risk factor in the occurrence of acute kidney injury after endovascular aneurysm repair

Acute kidney injury (AKI) is a complication that can occur during endovascular aneurysm repair (EVAR), increasing postoperative mortality and disease-related death. We therefore evaluated the incidence of AKI after elective EVAR, as well as related factors affecting AKI occurrence, investigating the volume of contrast medium (CV)/estimated glomerular filtration rate (eGFR) ratio as a predictive factor.We retrospectively reviewed the data of patients who underwent EVAR for infrarenal abdominal aorta aneurysm at a single center between April 2011 and December 2018. AKI was defined according to the Kidney Disease: Improving Global Outcomes criteria. We evaluated the occurrence of AKI within the first 7 days postoperatively, comparing serum creatinine levels, eGFR, CV, CV/eGFR ratio, fluid input and output, and morbidity between the AKI and no-AKI groups.The data of 147 patients were analyzed, of which 131 (89.1%) were males (mean age: 72.10±7.40 years); the incidence of AKI was 4.1% (6/147 patients). The mean dose of contrast agents used was greater in the AKI group than in the no-AKI group (249.17 ± 83.21 mL vs 179.43 ± 84.32 mL, respectively; P = .05). The baseline eGFR was 42.69 ± 22.08 mL/kg/1.73 m2 in the AKI group and 77.96 ± 18.92 mL/kg/1.73 m2 in the no-AKI group (P = .001). The CV/eGFR ratio was significantly higher in the AKI group (8.21 ± 6.13 vs 2.46 ± 1.44; P = 0.003). Baseline eGFR (odds ratio [OR] = 0.922, P = .001) and the CV/eGFR ratio (OR = 2.049, P = .008) were observed to be factors related to the occurrence of AKI in the logistic regression analysis for patients' characteristics, operation-related factors, and renal outcomes. In the receiver operating characteristic curve analysis, the area under the curve of the CV/eGFR ratio was 0.856, indicating the greatest influence. A CV/eGFR ratio cutoff value of 3.84 was considered the most appropriate, with an 83.3% sensitivity and 83.0% specificity.The CV/eGFR ratio, rather than the absolute amount of contrast agents, was associated with the development of AKI after EVAR. The CV/eGFR ratio could be used as a possible indicator to limit the amount of contrast media required for the procedure.