Although renal stenting is the standard revascularization method for atherosclerotic renal artery stenosis (RAS) (FMD-RAS), stenting in fibromuscular dysplasia (FMD) RAS is usually limited to periprocedural complications of angioplasty and primary arterial dissection. The main aim of the study was to retrospectively analyze the immediate and long-term results of renal stenting versus angioplasty in patients with FMD.
Of 343 patients in the ARCADIA-POL registry, 58 patients underwent percutaneous treatment due to FMD-RAS (in 70 arteries). Percutaneous transluminal renal angioplasty (PTRA) was performed as an initial treatment in 61 arteries (PTRA-group), whereas primary stenting was undertaken in nine arteries (stent-group). Stent-related complications were defined as: in-stent restenosis > 50% (ISR); stent fracture; under-expansion; or migration.
In the PTRA-group, the initial restenosis rate was 50.8%. A second procedure was then performed in 22 arteries: re-PTRA (12 arteries) or stenting (10 arteries). The incidence of recurrent restenosis after re-PTRA was 41.7%. Complications occurred in seven of 10 (70%) arteries secondarily treated by stenting: two with under-expansion and five with ISR. In the stent-group, stent under-expansion occurred in one case (11.1%) and ISR in three of nine stents (33.3%). In combined analysis of stented arteries, either primarily or secondarily, stent-related complications occurred in 11/19 stenting procedures (57.9%): three due to under-expansion and eight due to ISRs. Finally, despite several revascularization attempts, four of 19 (21%) stented arteries were totally occluded and one was significantly stenosed at follow-up imaging.
Our study indicates that renal stenting in FMD-RAS may carry a high risk of late complications, including stent occlusion. Further observational data from large-scale registries are required.

OBJECTIVE: To evaluate the 9-month safety and effectiveness outcomes of the Formula™ balloon-expandable renal stent (Cook Medical, Bloomington, IN) for the treatment of atherosclerotic renal artery stenosis (RAS) following suboptimal angioplasty.
BACKGROUND: Atherosclerotic RAS can cause hypertension and ischemic nephropathy. When clinically indicated, an interventional approach with renal angioplasty and stent implantation is the preferred method for revascularization of atherosclerotic renal artery stenoses.
METHODS: The REFORM study is a prospective, multicenter, single-arm study of stent implantation following suboptimal PTRA using the Formula stent. One hundred patients with atherosclerotic ostial renal artery lesions =18 mm in length with a >50% residual stenosis following PTA were enrolled. The primary endpoint was 9-month primary patency.
RESULTS: The 9-month primary patency rate was 91.7%. The 9-month major adverse event rate was 2.2%. Mean systolic blood pressure was significantly decreased at follow-up (from 150 ± 21 mm Hg at baseline to 141 ± 21 mm Hg at 9 months; P = 0.003). Mean serum creatinine (SCr) level and mean estimated glomerular filtration rate (eGFR) were not significantly different at 9 months. A clinically meaningful improvement in renal function (i.e., =25% increase in eGFR or =0.5 mg/dl decrease in SCr) was observed in 9% of patients at 1 month and 12% of patients at 9 months. A clinically meaningful decline in renal function (i.e., =25% decrease in eGFR or =0.5 mg/dl increase in SCr) was observed in only 3% of patients at 1 month and 7% of patients at 9 months.
CONCLUSIONS: The Formula stent was safe and effective in treating atherosclerotic RAS following suboptimal angioplasty.