Are Covered Renal Stents Protective Against Late Renal Artery Stenosis or Occlusion?

Amit Kumar, MD, Roy K. Greenberg, MD, Catherine Francis, Vikram S. Kashyap, MD, Kate Pfaff, Leslie Geiger, RN, Ethan Katz
Vascular Surgery, Cleveland Clinic Foundation, Cleveland, OH

Objective: Several studies have assessed the safety and efficacy of renal stenting to treat renovascular hypertension or insufficiency. Restenosis rates have ranged from 10-16%, with most events occurring within 2 years of treatment. The aim of this study was to compare renal specific outcomes between patients treated with covered versus uncovered renal stents.
Methods: Patients were enrolled in a prospective non-randomized study between 2001-2006 evaluating endovascular stent-grafts for treatment of juxtarenal (JAA) or thoracoabdominal (TAA) aortic aneurysms. Patients were treated with aortic devices coupled with uncovered (JAA) or ePTFE covered (TAA) balloon expandable renal stents, mostly 7 mm in size. Patients were followed at 1, 6, 12, 24, and 36 months post procedure with the status of each renal artery assessed by both duplex and contrast-enhanced CT. A conglomerate endpoint, consisting of new onset renal stenosis or occlusion, was evaluated with life-table techniques in an effort to contrast renal events in patients treated with covered versus uncovered devices.
Results: Since 2001, 225 patients were enrolled, 145 with JAA and 80 with TAA. Mean follow-up was 22 months for JAA and 7 months for TAA. Imaging follow-up data was available in 79.8 % pts (mean) at each time interval. A total of 13 renal arterial events occurred during follow-up, 12 in the JAA group (8 stenoses and 4 occlusions), and only 1 (8%) in the TAA group (an occlusion). 62% of the renal arterial events occurred during the first 12 months postoperatively. The estimated freedom from adverse renal arterial events for all patients was 94% and 90% at 12 and 24 months, respectively, by life table analyses.
Conclusions: The placement of uncovered stents into renal arteries coupled with endovascular stent-grafts to treat JAA leads to a low incidence of renal arterial problems. Renal arterial events are decreased further with the use of covered stents. The use of covered stents may prevent restenosis and should be studied in patients with renal artery occlusive disease undergoing intervention.