TCT: Peripheral DES trumps BMS and PTA in Zilver PTX trial

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Image source: Cook Medical

WASHINGTON, D.C.—Use of the Zilver PTX (paclitaxel) drug-eluting stent (Cook Medical) in comparison to the Zilver bare-metal stent (BMS) reduced restenosis rates by 63 percent, and proved to have better outcomes than primary percutaneous transluminal angioplasty (PTA) for femoropopliteal peripheral artery disease (PAD) patients, according to the results of the Zilver PTX late-breaking clinical trial presented Sept. 24 at the 22nd annual Transcatheter Cardiovacular Therapeutics (TCT) scientific meeting.

Michael D. Dake, MD, of the Stanford University School of Medicine, the principal investigator of the trial, said that the Zilver PTX study is the largest, randomized trial to evaluate the endovascular treatment of PAD patients.

The trial randomized 479 patients at 55 sites in three countries to receive either the Zilver drug-eluting PTX stent device (n=248) or balloon angioplasty (n=238). The researchers evaluated primary safety and efficacy endpoints, including primary patency at 12 months.

At 12 months, patency rates were 83.1 percent for patients within the DES arm and 32.8 percent in the primary PTA arm, according to Dake.

Due to higher failure rate of primary PTA, researchers evaluated patients who experienced optimal PTA and found they had a patency rate of 65.3 percent at 12 months

Researchers then performed a secondary analysis that compared the primary Zilver PTX with provisional BMS in those patients with suboptimal PTA at 12 months and found the patency rates to be 83 versus 67 percent, which translated into a 49 percent reduction in restenosis.

Patency rates at 12 months for provisional placement of Zilver PTX compared with provisional BMS were 89.9 versus 73 percent. This translated into a 63 percent reduction in the rate of restenosis at 12 months for the drug eluting stent.

“This trial design was unique and allowed a secondary randomization.… Patients who failed PTA went on to be randomized again to either a bare stent or the Zilver PTX stent.… Because of the high rate of PTA there were actually a fairly large number for the peripheral trial and the secondary randomization was able to compare 62 lesions with BMS to 63 with the Zilver PTX,” Dake explained.

Dake noted they found a stent fracture rate of less than 1 percent during the trial.

“If we look at primary Zilver PTX, stenting resulted in significant better patency rate than PTA, the primary endpoint, but also had significantly higher patency compared to optimal PTA and standard of care,” he said.

“I think it represents a differentiated moment in terms of our approach to therapies,” said Dake. “As you know, DES in the coronary arteries is obviously well adopted and used regularly, but in the peripheral market it has been a little longer coming.”

Dake said that this could be because these facilitate the use of a completely different type of stent, which are self-expanding rather than balloon expandable. Additionally, he said that only two other previous DES trials to study the endovascular treatment of PAD have been conducted, and did not show promising results.

“I think for the first time we seem to have a signal that it is possible to improve results of current therapies with combinations of drugs and stents,” he concluded.

Angiotech Pharmaceuticals also announced that the current trial met its primary endpoint goals of non-inferior event-free survival and superior patency for the Zilver PTX when compared to PTA.

Cook Medical is the licensed holder of the Zilver PTX device and sponsored the trial.