The U.S. Food and Drug Administration approved the Zilver PTX Drug-Eluting Peripheral Stent (Zilver PTX Stent), the first drug-eluting stent indicated to re-open a particular artery in the thigh (femoropopliteal artery) when narrowed or blocked as a result of peripheral artery disease (PAD).
PAD occurs when fatty material (plaque) builds up in the arteries that carry blood to the head, organs and limbs, usually affecting 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, including skin ulcers or gangrene.
The Zilver PTX Stent includes a small, metal mesh tube called a self-expanding metal stent that keeps an artery open. The stent is coated on its outer surface with the drug paclitaxel, a drug that helps prevent recurrent narrowing of arteries (restenosis). Existing options for treatment of PAD can include exercise, drug therapy, and other options within the artery, such as percutaneous transluminal angioplasty (PTA, or balloon angioplasty), or bare-metal stenting or surgical bypass.
“The clinical study demonstrated that the Zilver is more effective than balloon angioplasty for the treatment of symptomatic peripheral artery disease in above-the-knee femoropopliteal artery,” said Christy Foreman, director of the Office of Device Evaluation at FDA’s Center for Devices and Radiological Health. “This approval expands the treatment options for patients suffering from symptomatic peripheral artery disease to include the Cook Zilver PTX drug eluting stent.”
Data supporting the safety and effectiveness of the stent came from extensive non-clinical testing including biocompatibility, bench, and animal testing, as well as a clinical trial program.
One clinical trial compared the safety and effectiveness of the Zilver PTX stent to PTA and bare-metal stenting. This study enrolled 479 patients with a single stenotic lesion less than 140 mm long in one or both of their femoropopliteal arteries. Patients randomly received the Zilver PTX or underwent PTA. If PTA failed, the patient then randomly received either a Zilver PTX or a bare metal stent that did not have the paclitaxel coating.
At the end of 12 months, 83 percent of narrowings treated with the Zilver PTX stent were still open, compared with 33 percent in the PTA control group. Among patients who failed the PTA treatment, 90 percent of narrowings treated with the Zilver PTX were open at 12 months compared with 73 percent for those treated with the bare metal stent.
In a separate study, researchers enrolled 787 patients in a 12-month clinical trial where patients could receive up to four Zilver PTX stents for treating a single or multiple lesions. Researchers detected stent fractures in 1.54 percent of Zilver PTX stents at 12 months. The stent fractures did not result in any detectable clinical consequences. The rate of stent thrombosis was 2.8 percent at 12 months and 3.5 percent 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 device is contraindicated (should not be used) in patients with stenoses that cannot be dilated to permit passage of the catheter or proper placement of the stent, patients who cannot receive recommended drug therapy due to bleeding disorders, or women who are pregnant, breastfeeding, or plan to become pregnant in the next five years.
As part of the approval, the FDA is requiring the manufacturer to conduct a five-year post-approval study of 900 patients treated with the Zilver-PTX Stent to further monitor safety and efficacy.
The Zilver PTX Stent is manufactured by Cook Incorporated of Bloomington, Ind.