Renal Artery Stent Outcomes: Effect of Baseline Blood Pressure, Stenosis Severity, and Translesion Pressure Gradient

Abstract

Background: Multiple randomized clinical trials comparing renal artery stent placement plus medical therapy with medical therapy alone have not shown any benefit of stent placement. However, debate continues whether patients with extreme pressure gradients, stenosis severity, or baseline blood pressure benefit from stent revascularization.

Objectives: The study sought to test the hypothesis that pressure gradients, stenosis severity, and/or baseline blood pressure affects outcomes after renal artery stent placement.

Methods: Using data from 947 patients with a history of hypertension or chronic kidney disease from the largest randomized trial of renal artery stent placement, the CORAL (Cardiovascular Outcomes in Renal Atherosclerotic Lesions) study, we performed exploratory analyses to determine if subsets of patients experienced better outcomes after stent placement than the overall cohort. We examined baseline stenosis severity, systolic blood pressure, and translesion pressure gradient (peak systolic and mean) and performed interaction tests and Cox proportional hazards analyses for the occurrence of the primary endpoint through all follow-up, to examine the effect of these variables on outcomes by treatment group.

Results: There were no statistically significant differences in outcomes based on the examined variables nor were there any consistent nonsignificant trends.

Conclusions: Based on data from the CORAL randomized trial, there is no evidence of a significant treatment effect of the renal artery stent procedure compared with medical therapy alone based on stenosis severity, level of systolic blood pressure elevation, or according to the magnitude of the trans-stenotic pressure gradient. (Benefits of Medical Therapy Plus Stenting for Renal Atherosclerotic Lesions [CORAL]; NCT00081731).

Keywords: chronic kidney disease; hypertension; renal artery; stenosis; stent.

Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Figures

FIGURE 1. Freedom From the Primary Composite Endpoint Over Time in the CORAL Study Subgroups

Forest plots displaying treatment effects within subgroups by quartiles (A) and by historic clinical thresholds (B): baseline percent stenosis (core lab), baseline percent stenosis (investigator), baseline systolic blood pressure (SBP), baseline peak systolic pressure gradient, baseline mean systolic pressure gradient (rates of primary endpoint composite through all available follow-up). The p values for rows labeled as percent stenosis, peak systolic pressure gradient, mean systolic pressure gradient, and baseline SBP are treatment-by-subgroup interaction p values. The rest of the p values are for remaining subgroups. CI = confidence interval; CORAL = Cardiovascular Outcomes in Renal Atherosclerotic Lesions.

FIGURE 2. Freedom From the Primary Endpoint by Subgroup in the CORAL Study

(A) Event-free Kaplan-Meier curves for primary endpoint composite through 5 years of follow-up by treatment group for each baseline percent stenosis as reported by the core lab quartile category (<60.22, 60.22 to <68.46, 68.46 to <77.05, ≥77.05 mm Hg). Log-rank test between groups for first quartile (<60.22) = 0.4895. Log-rank test between groups for second quartile = 0.4780. Log-rank test between groups for third quartile = 0.3065. Log-rank test between groups for fourth quartile = 0.1487. The p value is for all available follow-up (not limited to 5 years). (B) Event-free Kaplan-Meier curves for primary endpoint composite through 5 years of follow-up by treatment group for each baseline percent stenosis as determined by the core lab by clinically significant category (<60, 60 to <80, ≥80 mm Hg). Log-rank test between groups for first category (<60) = 0.3992. Log-rank test between groups for second category = 0.1023. Log-rank test between groups for third category = 0.2487. The p value is for all available follow-up (not limited to 5 years). (C) Event-free Kaplan-Meier curves for primary endpoint composite through 5 years of follow-up by treatment group for each baseline percent stenosis as reported by the investigator quartile category (<69.7, 69.7 to <76, 76 to <85, ≥85 mm Hg). Log-rank test between groups for first quartile (<69.7) = 0.7703. Log-rank test between groups for second quartile = 0.0710. Log-rank test between groups for third quartile = 0.5734. Log-rank test between groups for fourth quartile = 0.8009. The p value is for all available follow-up (not limited to 5 years). (D) Event-free Kaplan-Meier curves for primary endpoint composite through 5 years of follow-up by treatment group for each baseline percent stenosis as reported by the investigator category (60 to <80, ≥80 mm Hg). Log-rank test between groups for first category (<60) = N/A (there was no patient in Med Rx group, so the p value is not available). Log-rank test between groups for second category = 0.2736. Log-rank test between groups for third category = 0.6663. The p value is for all available follow-up (not limited to 5 years). CORAL = Cardiovascular Outcomes in Renal Atherosclerotic Lesions.

FIGURE 2. Freedom From the Primary Endpoint by Subgroup in the CORAL Study

(A) Event-free Kaplan-Meier curves for primary endpoint composite through 5 years of follow-up by treatment group for each baseline percent stenosis as reported by the core lab quartile category (<60.22, 60.22 to <68.46, 68.46 to <77.05, ≥77.05 mm Hg). Log-rank test between groups for first quartile (<60.22) = 0.4895. Log-rank test between groups for second quartile = 0.4780. Log-rank test between groups for third quartile = 0.3065. Log-rank test between groups for fourth quartile = 0.1487. The p value is for all available follow-up (not limited to 5 years). (B) Event-free Kaplan-Meier curves for primary endpoint composite through 5 years of follow-up by treatment group for each baseline percent stenosis as determined by the core lab by clinically significant category (<60, 60 to <80, ≥80 mm Hg). Log-rank test between groups for first category (<60) = 0.3992. Log-rank test between groups for second category = 0.1023. Log-rank test between groups for third category = 0.2487. The p value is for all available follow-up (not limited to 5 years). (C) Event-free Kaplan-Meier curves for primary endpoint composite through 5 years of follow-up by treatment group for each baseline percent stenosis as reported by the investigator quartile category (<69.7, 69.7 to <76, 76 to <85, ≥85 mm Hg). Log-rank test between groups for first quartile (<69.7) = 0.7703. Log-rank test between groups for second quartile = 0.0710. Log-rank test between groups for third quartile = 0.5734. Log-rank test between groups for fourth quartile = 0.8009. The p value is for all available follow-up (not limited to 5 years). (D) Event-free Kaplan-Meier curves for primary endpoint composite through 5 years of follow-up by treatment group for each baseline percent stenosis as reported by the investigator category (60 to <80, ≥80 mm Hg). Log-rank test between groups for first category (<60) = N/A (there was no patient in Med Rx group, so the p value is not available). Log-rank test between groups for second category = 0.2736. Log-rank test between groups for third category = 0.6663. The p value is for all available follow-up (not limited to 5 years). CORAL = Cardiovascular Outcomes in Renal Atherosclerotic Lesions.

CENTRAL ILLUSTRATION. Renal Artery Stent Outcomes: Subgroups Analysis From the CORAL Study

Forest plot displaying treatment effects within clinical-threshold subgroups: baseline percent stenosis (core lab), baseline systolic blood pressure (SBP), and baseline peak systolic pressure gradient. The p values for rows labeled as percent stenosis, peak systolic pressure gradient, and baseline SBP are treatment-by-subgroup interaction p values. The rest of the p values are for remaining subgroups. CORAL = Cardiovascular Outcomes in Renal Atherosclerotic Lesions.