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FDA Approves First Drug-Eluting Stent for Peripheral Arterial Disease
The FDA has approved the Zilver PTX Drug-Eluting Peripheral Stent (Cook Incorporated) — the first drug-eluting stent indicated to re-open the femoropopliteal artery in the thigh when the vessel is narrowed or blocked as a result of peripheral artery disease (PAD).
PAD occurs when fatty plaque builds up in the arteries that carry blood to the head, organs, and limbs, and usually affects the arteries in the legs. This causes hardening and/or narrowing of the arteries (atherosclerosis), limiting the flow of oxygen-rich blood to the body. People with PAD may experience lifestyle-limiting symptoms, such as leg pain, or serious complications, such as skin ulcers or gangrene.
The Zilver PTX stent includes a small, metal mesh tube — a self-expanding stent — that keeps the artery open. The stent is coated on its outer surface with paclitaxel, which helps prevent restenosis. The current treatment of PAD includes exercise, drug therapy, and other options within the artery, such as percutaneous transluminal angioplasty (PTA, also known as balloon angioplasty), bare-metal stenting, or surgical bypass.
Data supporting the safety and effectiveness of the new stent came from extensive nonclinical testing, including biocompatibility, bench, and animal testing, as well as a clinical-trials program.
One clinical study compared the safety and efficacy of the Zilver PTX stent with that of PTA and bare-metal stents The study enrolled 479 patients with a single stenotic lesion less than 140 mm long in one or both of their femoropopliteal arteries. The patients were randomly assigned to receive either the Zilver PTX stent or PTA. If the PTA failed, the patient randomly received either a Zilver PTX stent or a bare-metal stent that did not have the paclitaxel coating.
After 12 months, 83% of arterial narrowings treated with the Zilver PTX stent were still open, compared with 33% in the PTA control group. Among patients who failed treatment with PTA, 90% of arterial narrowings treated with the Zilver PTX stent were open at 12 months, compared with 73% for those treated with the bare-metal stent.
In another study, researchers treated 787 patients with up to four Zilver PTX stents for single or multiple lesions. Stent fractures were detected in 1.5% of the Zilver PTX stents at 12 months. The stent fractures did not result in any detectable clinical consequences. The rates of stent thrombosis were 2.8% at 12 months and 3.5% at 24 months. The study results indicate that treatment with the Zilver PTX stent is at least as safe as treatment with PTA and significantly more effective.
In both studies, the most common major adverse event was restenosis requiring additional treatment to re-establish adequate flow in the artery.
The Zilver PTX stent is contraindicated in patients with stenoses that cannot be dilated to permit passage of the catheter or proper placement of the stent; in patients who cannot receive recommended drug therapy because of bleeding disorders; or in women who are pregnant, breastfeeding, or plan to become pregnant in the next 5 years.
As part of the approval, the FDA is requiring the manufacturer to conduct a 5-year post-approval study of 900 patients treated with the Zilver PTX stent to further monitor safety and efficacy.
Source: FDA; November 15, 2012.