Predicting Renal Function Response to Renal Artery Stenting
J. Gregory Modrall1, Haekyung Jeon-Slaughter2, Shirling Tsai1, Bala Ramanan1, Richard Miller, III1, Jeffrey Hastings2
1University of Texas Southwestern Medical Center, Dallas, TX;2Dallas VA Medical Center, Dallas, TX
INTRODUCTION: The CORAL Trial found no benefit of renal artery stenting (RAS) over medical therapy, although it was under-powered to detect a benefit among patients with chronic kidney disease (CKD). Post hoc analysis demonstrated improved event-free survival after RAS for patients whose renal function improved ≥ 20%. The obstacle to achieving this benefit is the inability to predict which patients’ renal function will improve from RAS. The objective of the current study was to identify predictors of renal function response to RAS that may facilitate patient selection.
METHODS: The Veteran Affairs Clinical Data Warehouse was queried for patients who underwent RAS between 2000-2021. The primary outcome was improvement in renal function (estimated glomerular filtration rate, eGFR) after stenting. Patients were categorized as “responders” if eGFR at 30-90 days post-stenting increased ≥20%, compared to pre-stenting. All others were “non-responders.”
RESULTS: The study cohort included 695 patients. 202 (29.1%) were responders. Table 1 includes the pre-stenting characteristics of responders and non-responders. Prior to RAS, responders had a significantly higher mean serum creatinine, lower mean eGFR, and higher rate of decline of preoperative GFR over the 25 weeks before RAS (Table 1). Figure 1 shows eGFR immediately before stenting and continuing to last follow-up (mean 54 ±41 months). During follow-up, responders had a 34.4% increase in eGFR, compared to pre-stenting (P<0.0001), which remained stable. Non-responders had a progressive 10.2% decrease in eGFR after stenting. Logistic regession analysis identified two predictors of renal function response to stenting: 1) CKD stages 3b or 4 [Odd Ratio (OR) 2.60, 95% Confidence Interval (CI) 1.33-5.11; P=0.01; and 2) rate of decline in preoperative eGFR prior to stenting (OR 3.71, 05% CI 1.04-13.28; P=0.04). Other variables, including gender, age, and race/ethnicity, had no effect. The impact of proteinuria (urine albumin/creatinine ratio) on the outcomes for RAS remains unknown because of missing data and the heterogeneity of the laboratory assays in our dataset. The area under the curve for the receiver operating characteristics (ROC) curve of the model was 0.70.
CONCLUSIONS: Based on our data, patients in CKD stages 3b and 4 (eGFR 15-44 mL/min/1.73m2) are the only sub-groups with a significant probability of improved renal function after RAS. Among patients in CKD stages 3b or 4, the rate of decline of preoperative eGFR over the 6 months prior to stenting is a powerful discriminator of patients who are most likely to benefit from RAS. Specifically, patients with a more rapid decline in eGFR over the 6 months prior to stenting have a significantly higher probability of improved renal function with RAS. 
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