Retrieval of Renal Function After Renal Artery Stenting Improves Event-Free Survival in a Sub-group Analysis of the Cardiovascular Outcomes in Renal Atherosclerotic Lesions Trial

MRI-Based Radiomics to Predict Renal Function Response to Renal Artery Stenting for Atherosclerotic Renal Artery Stenosis

PURPOSE

To investigate magnetic resonance imaging (MRI)-based radiomics for predicting renal function response for patients treated for atherosclerotic renal artery stenosis (ARAS) by endoluminal means.

MATERIAL AND METHODS

A cohort of 146 ARAS patients who underwent stenting was analyzed, with retrospective training and prospective validation groups delineated based on the treatment timing. Patients were categorized into benefit and no-benefit groups based on postoperative renal function during follow-up. Optimal radiomics labels were selected from regions of interest (ROIs) including the stenotic side and both kidneys. The nomogram combined optimal radiomics signatures with independent clinical factors using multivariable logistic regression. Shapley Additive exPlanations (SHAP), decision curve analysis (DCA), the net reclassification index (NRI), and the total integrated discrimination index (IDI) were conducted to determine the clinical usefulness of the nomogram.

RESULTS

Split renal function of the stenotic side and diabetes emerged as independent clinical predictors. A nomogram, incorporating these clinical factors and radiomics features from the stenotic side and both kidneys, achieved area under the curve (AUCs) of 0.927 (0.861-0.979) and 0.904 (0.819-0.972) in the training and test groups, respectively, for predicting benefits. The clinical-radiomics model significantly improved diagnostic performance (p = 0.001 and p = 0.011 for the training and test groups, respectively). DCA, NRI, and IDI analyses suggested the nomogram's superiority. SHAP analysis highlighted the radiomics feature from stenotic side kidney as the most critical predictive feature.

CONCLUSIONS

Both MRI radiomics and clinical factors may be valuable in pre-treatment counseling of ARAS patients who may benefit from endovascular treatment.

Hypertensive load predicts recovery of renal function for patients undergoing revascularisation for renal artery stenosis

Renal ischaemia due to renal artery stenosis produces two differing responses - a juxtaglomerular hypertensive response and cortical renal dysfunction. The reversibility of renal impairment is not predictable, and thus renal revascularisation is controversial. This study aims to test the hypothesis that the hypertensive response to renal ischaemia reflects viable renal parenchyma, and thus could be used to predict the recovery in renal function. A retrospective analysis was performed of all patients who had renal revascularisation for renal impairment in a defined geographical area (West of Scotland, population 2.4 million) between 2008 and 2024. Clinical records were used to determine the pre-intervention blood pressure, anti-hypertensive medication load and renal function, and post-intervention outcomes. The Hypertensive Index (HTi), a combined measure of systolic blood pressure and antihypertensive drug load, was used as a measure of pre-intervention hypertensive response. 75 patients had intervention for renal impairment over 15 years (68 endovascular, 7 open). Mean pre-intervention serum creatinine of 323 µmol/L was reduced to 191 umol/L at discharge and 182 µmol/L at 6-month follow-up. Refractory hypertension (HTi > 120) was associated with a significant benefit from revascularisation with improved renal function (p = 0.003) and reduced risk of future dialysis (p = 0.001). Renal impairment with no hypertensive response was highly predictive of the need for future dialysis. The hypertensive index is a good predictor of the impact of renal revascularisation on improving renal function with good outcomes in selected patients, and the absence of this is an indicator of chronic non-reversible renal dysfunction.

Evaluation of the therapeutic efficacy of renal artery stenting in patients with atherosclerotic renal artery stenosis

PURPOSE

It is currently controversial whether renal artery stenting is beneficial for the clinical outcomes of atherosclerotic renal artery stenosis (ARAS) patients. The study aims to evaluate whether blood pressure (BP) and renal function improve in ARAS patients after stenting.

METHODS

A retrospective study was conducted on 78 ARAS patients who underwent renal artery stenting at the First Affiliated Hospital of Chongqing Medical University from January 2013 to June 2024. BP, the number of oral antihypertensive medications, renal function, and adverse events were analyzed before and after stenting.

RESULTS

A total of 90 stents were implanted. The median follow-up time was 1.59 years. From 24 hours post-operation, significant decline in BP were observed. During follow-up, systolic BP decreased by 24.27 mmHg (95% CI: 16.54-32.00; P < 0.0001) and diastolic BP by 12.27 mmHg (95% CI: 7.25-17.29; P < 0.0001), but the reduction in the number of oral antihypertensive medications was not significant (P > 0.05). Serum creatinine also showed a significant decrease of 8.50 μmol/L at follow-up (P < 0.05). Among the four subgroups, 30 patients with mild renal impaired [eGFR ≥ 60 mL/(min·1.73 m2) and <90 mL/(min·1.73 m2)] showed an increase of 10.68 mL/(min·1.73 m2) in eGFR during follow-up (P < 0.01), while the eGFR of the remaining 48 patients with other renal function stages showed no significant change before and after stenting. Moreover, 24 patients experienced cardiovascular or/and renal adverse events.

CONCLUSIONS

Renal artery stenting might significantly reduce BP and improve renal function in ARAS patients, particularly those with mild renal impairment, which still requires prospective multicenter studies to confirm.

CT-based radiomics: predicting early outcomes after percutaneous transluminal renal angioplasty in patients with severe atherosclerotic renal artery stenosis

This study aimed to comprehensively evaluate non-contrast computed tomography (CT)-based radiomics for predicting early outcomes in patients with severe atherosclerotic renal artery stenosis (ARAS) after percutaneous transluminal renal angioplasty (PTRA). A total of 52 patients were retrospectively recruited, and their clinical characteristics and pretreatment CT images were collected. During a median follow-up period of 3.7 mo, 18 patients were confirmed to have benefited from the treatment, defined as a 20% improvement from baseline in the estimated glomerular filtration rate. A deep learning network trained via self-supervised learning was used to enhance the imaging phenotype characteristics. Radiomics features, comprising 116 handcrafted features and 78 deep learning features, were extracted from the affected renal and perirenal adipose regions. More features from the latter were correlated with early outcomes, as determined by univariate analysis, and were visually represented in radiomics heatmaps and volcano plots. After using consensus clustering and the least absolute shrinkage and selection operator method for feature selection, five machine learning models were evaluated. Logistic regression yielded the highest leave-one-out cross-validation accuracy of 0.780 (95%CI: 0.660-0.880) for the renal signature, while the support vector machine achieved 0.865 (95%CI: 0.769-0.942) for the perirenal adipose signature. SHapley Additive exPlanations was used to visually interpret the prediction mechanism, and a histogram feature and a deep learning feature were identified as the most influential factors for the renal signature and perirenal adipose signature, respectively. Multivariate analysis revealed that both signatures served as independent predictive factors. When combined, they achieved an area under the receiver operating characteristic curve of 0.888 (95%CI: 0.784-0.992), indicating that the imaging phenotypes from both regions complemented each other. In conclusion, non-contrast CT-based radiomics can be leveraged to predict the early outcomes of PTRA, thereby assisting in identifying patients with ARAS suitable for this treatment, with perirenal adipose tissue providing added predictive value.

Atherosclerotic renovascular disease: a clinical practice document by the European Renal Best Practice (ERBP) board of the European Renal Association (ERA) and the Working Group Hypertension and the Kidney of the European Society of Hypertension (ESH)

Atherosclerotic renovascular disease (ARVD) is the most common type of renal artery stenosis. It represents a common health problem with clinical presentations relevant to many medical specialties and carries a high risk for future cardiovascular and renal events, as well as overall mortality. The available evidence regarding the management of ARVD is conflicting. Randomized controlled trials failed to demonstrate superiority of percutaneous transluminal renal artery angioplasty (PTRA) with or without stenting in addition to standard medical therapy compared with medical therapy alone in lowering blood pressure levels or preventing adverse renal and cardiovascular outcomes in patients with ARVD, but they carried several limitations and met important criticism. Observational studies showed that PTRA is associated with future cardiorenal benefits in patients presenting with high-risk ARVD phenotypes (i.e. flash pulmonary oedema, resistant hypertension or rapid loss of kidney function). This clinical practice document, prepared by experts from the European Renal Best Practice (ERBP) board of the European Renal Association (ERA) and from the Working Group on Hypertension and the Kidney of the European Society of Hypertension (ESH), summarizes current knowledge in epidemiology, pathophysiology and diagnostic assessment of ARVD and presents, following a systematic literature review, key evidence relevant to treatment, with an aim to support clinicians in decision making and everyday management of patients with this condition.

Predicting renal function response to renal artery stenting

OBJECTIVE

The Cardiovascular Outcomes in Renal Atherosclerotic Lesions Trial found no benefit of renal artery stenting (RAS) over medical therapy, although it was underpowered to detect a benefit among patients with chronic kidney disease (CKD). A post hoc analysis demonstrated improved event-free survival after RAS for patients whose renal function improved by 20% or more. A significant obstacle to achieving this benefit is the inability to predict which patients' renal function will improve from RAS. The objectives of the current study were to identify predictors of renal function response to RAS.

METHODS

The Veteran Affairs Corporate Data Warehouse was queried for patients who underwent RAS between 2000 and 2021. The primary outcome was improvement in renal function (estimated glomerular filtration rate [eGFR]) after stenting. Patients were categorized as responders if the eGFR at 30 days or greater after stenting increased by 20% or more compared with before stenting. All others were nonresponders.

RESULTS

The study cohort included 695 patients with a median follow-up of 7.1 years (interquartile range, 3.7-11.6 years). Based on postoperative change in eGFR, 202 stented patients (29.1%) were responders, and the remainder (n = 493 [70.9%]) were nonresponders. Before RAS, responders had a significantly higher mean serum creatinine, lower mean eGFR, and higher rate of decline of preoperative GFR in the months before stenting. After stenting, responders had a 26.1% increase in eGFR, compared with before stenting (P < .0001), which remained stable during follow-up. In contrast, nonresponders had a progressive 5.5% decrease in eGFR after stenting. Logistic regression analysis identified three predictors of renal function response to stenting: (1) diabetes (odds ratio [OR], 0.64; 95% confidence interval [CI], 0.44-0.91; P = .013), (2) CKD stages 3b or 4 (OR, 1.80; 95% CI, 1.26-2.57; P = .001), and (3) rate of decline in preoperative eGFR per week before stenting (OR, 1.21; 95% CI, 1.05-1.39; P = .008). CKD stages 3b and 4 and the rate of decline in preoperative eGFR are positive predictors of renal function response to stenting, whereas diabetes is a negative predictor.

CONCLUSIONS

Based on our data, patients in CKD stages 3b and 4 (eGFR 15-44 mL/min/1.73 m2) are the only subgroups with a significant probability of improved renal function after RAS. The rate of decline of preoperative eGFR over the months before stenting is a powerful discriminator of patients who are most likely to benefit from RAS. Specifically, patients with a more rapid decrease in eGFR before stenting have a significantly greater probability of improved renal function with RAS. In contrast, diabetes is a negative predictor of improved renal function, so interventionalists should be circumspect about RAS in diabetic patients.