Created by Cook Medical, manufacturer of minimally-invasive medical device technology, the CE-Marked Zilver PTX Drug-Eluting Stent aims to improve the standard of care for patients with serious blockages in the superficial femoral artery (SFA) in the leg.

 

In the largest clinical trial of its kind ever conducted, the Zilver PTX stent was shown to effectively bridge the gap between the patient results achieved using open surgical bypass graft procedures and the less traumatic, but typically less effective minimally-invasive options currently available such as balloon angioplasty and bare metal stenting.

 

Rob Lyles, vice president and global leader of Cook Medical’s peripheral intervention unit, explained: “At the moment there are three main options for the treatment of SFA blockages. The first of these, open surgery, is generally successful 60-85% of the time and patients rarely need a re-intervention afterwards. This is a nice outcome, but it is major surgery and the patient has to be put under a general anaesthetic with the associated risks. The complication rate for infection following this procedure is 2-3%, but in some cases it can be up to 15%. Having surgery of this magnitude also extends the time a patient stays in hospital and recovery can take three months or more.

 

“There are also two minimally-invasive treatments, which by their nature cut down on the complication rate and recovery is generally quicker. The first of these is balloon angioplasty where the complication rate is 1% and patients can return to normal after as little as 24 hours, but the success rate in this case drops to 30-40%.

“The third option, the bare metal stent, again has a high success rate – between 60-80%, but can also lead to patients having to have re-interventions in the future.

 

“Now we also have a fourth option, the Zilver PTX, which is really very new and very different.”

 

The device, which was officially launched at the annual CIRSE meeting in Lisbon this week, has enjoyed a 85-90% success during trials, which included a number of high-risk patients such as diabetics and those for whom previous interventions have failed.

 

Lyles said: “With the Zilver PTX stent, we have introduced a true landmark device that can reduce the number of PAD patients having to endure the trauma of leg amputations and bypass surgeries.”

 

And this could have a huge impact on patients in the UK, which has one of the highest PAD amputation rates in Europe.

 

Lyles explained: “In most of western Europe, amputation rates for PAD are going down, but in the UK they are going up. The UK does more open surgery and less stenting than the rest of Europe, so while in Germany they might be putting in 50,000 femoral stents a year, in the UK that figure is around 4,000. This is a pretty dramatic difference and we are hoping the Zilver PTX will offer clinicians in the UK another option to consider.”

 

“In our trials we found that even for patients with in-stent restenosis and no other options left open to them, the Zilver PTX worked in three out of four cases. We have achieved a very powerful combination of a good drug and a good stent”

Unique to Cook Medical, the device is the first drug-eluting stent designed specifically for the treatment of PAD in the superficial femoral artery, the largest and most difficult-to-treat blood vessel in the leg. It works by expanding and holding open the artery to restore blood flow. The device then delivers the cancer drug paclitaxel (licensed from Angiotech Pharmaceuticals) to the cells in the vessel wall to reduce the risk of new blockages forming.

 

In a major advance over previous therapies, the Zilver PTX achieves targeted drug delivery without using a polymer to adhere the drug to the stent body. Instead the drug has been formulated to stick directly onto the cell wall where it effectively switches off those cells believed to cause scar tissue and inflammation that can cause new blockages (restenosis). This approach eliminates the potential patient risks associated with polymer-coated devices, including clot formation and inflammation.

 

Lyles said: “In our trials we found that even for patients with in-stent restenosis and no other options left open to them, the Zilver PTX worked in three out of four cases. We have achieved a very powerful combination of a good drug and a good stent.

 

“The stent itself is made from nitinol, which has shape memory, so regardless of movement it will return to its original form. This is particularly good as the SFA is a very hostile part of the anatomy which shortens, twists, bends and compresses so you need a device which can withstand these forces without changing. The body also has difficulties dealing with the polymer coating on other drug-eluting stents.”

 

Already awarded the CE Mark in 50 countries including the UK, Cook Medical’s team is currently working with government bodies to bring the Zilver PTX into the NHS supply chain.

 

Lyles said: “One key breakthrough is our commitment to a patient-focused strategy that should make the device available to virtually any PAD patient who needs it.

 

“As part of our ongoing corporate mission to help reduce global healthcare delivery costs, we have adopted a unique affordable innovation strategy aimed at reducing any potential financial reimbursement barriers to its widespread adoption as the standard treatment for PAD in this part of the body.”

“With the Zilver PTX stent, we have introduced a true landmark device that can reduce the number of PAD patients having to endure the trauma of leg amputations and bypass surgeries”

      

 

During the trials the stents were found to have a fracture rate of 1.8%, while the leading traditional stents have rates in the region of 26% and some as high as 50%.

 

“To be able to demonstrate not only accuracy of the combination, but to have data that demonstrates a low fracture rate is a very good position to be in,” said Lyle. “As preliminary results of the trial were released there was growing anticipation and excitement from clinicians.”