Gary Ansel, MD, is System Medical Director for Vascular Medicine at OhioHealth in Toledo, Ohio. At the 43rd VEITHsymposium, Dr. Ansel presented data from the randomized controlled trial studying the Zilver PTX drug-eluting stent (DES) (Cook Medical) vs percutaneous transluminal angioplasty and bare-metal stents. He shared new Findings from subanalyses as well as 5-year results that show widening benefits from the DES. Vascular Disease Management spoke with Dr. Ansel at the meeting about these results.
VDM: Can you share background about the Zilver PTX studies?
Ansel: Zilver was the first multicenter randomized trial as well as large Japanese registry that looked at drug-coated stents vs plain balloon angioplasty. A subanalysis was performed of drug-coated stents vs bare-metal stents for patients who failed initial angioplasty. We now have up to 5 years of results for the randomized patient population.
VDM: What are the subanalyses that we are talking about here?
Ansel: There were two big subanalyses that we performed, because we often hear that run-off vessels can decrease or increase your patency — depending on the number of patent vessels.The other subanalysis was of renal failure patients. These patients are usually excluded from trials. Gaining knowledge on these patient populations has always been important to us.
VDM: What were some of the remarkable findings from the subanalyses?
Ansel: Interestingly, when we look at how the run-off vessels affect patency, we found no association for drug-eluting stent (DES) patency. So not having run-off vessels didn’t affect patency. This is the first time we’ve seen that documented for DES. Also, patients with renal dysfunction didn’t have any decrease in patency, contrary to what we may have predicted. There was a trend toward increased patency. Perhaps this may be due to some platelet dysfunction that could be there; this is still an unknown but interesting finding.
VDM: How dramatic were the differences between the two groups being studied?
Ansel: There wasn’t any statistical difference whatsoever. Statistically, there was no difference between the groups on either side.
VDM: How do you think this could inform future practice for endovascular clinicians?
Ansel: I think this puts the impetus on other devices and different trials to look at these subgroup populations as well, because as we do our trials we typically exclude patients with less than one run-off vessel from the trial, so for many of our patients we don’t know what the results would be as we use the devices in real world patients. We also need more information on renal insufficiency patients. We are trying to figure out where they fit in the endovascular treatment or surgical treatment arms and this kind of information is important to us. We need to start looking at our trials a little differently now.
VDM: In what way could future trials address the question?
Ansel: In the future, other trials could address this by looking at similar populations, they could consider registry arms for the patient population with less than one run-off vessel to see if the technology holds up for that population. And we usually exclude patients who don’t have good renal function, so broadening that out would give us critical information. Allowing us to add those patients to the trials, such as with a registry arm with this risk stratification to see if that technology is affected by renal function or not would be very useful.
VDM: Drug-eluting technologies have come a long way in the last few years. How do you think the DES fits into the related devices now in the algorithm?
Ansel: The DES technology was the first drug-coated technology in the United States. It’s now available throughout the world. We also have drug-coated balloons. The question is, will the drug-coated balloon have the same durability that we’ve seen in the DES studies? And that’s not a given. If you think about it, for the calcified vessel, it doesn’t look like drug-eluting balloons do very well for the moderately severe to severe calcification where it did not seem to affect DES. We still need to find out what technology is best for each individual patient population.
VDM: Could you elaborate on the 5-year results and the further benefit you saw in that time?
Ansel: The other interesting finding from the Zilver PTX trial as time has passed is that there was not only an improvement in the lack of need for repeat procedures (48%) but the difference between the control or standard of care in the DES group continued to widen. This widened between 1 year and 5 years by 35%. In other words, instead of having just an early initial effect, this had a higher effect at 5 years, so that’s more evidence in support of drug-coated technologies, and I don’t think drugs are ever going to go away. That’s the way it is.
VDM: Is there anything else you want to add that you think is important for endovascular clinicians to know about the results or Zilver PTX?
Ansel: The other subgroup analysis that we looked at were the patients who did get restenosis and what we found is that there was about a 39% reduction in plaque burden in that group, which might decrease how hard it is to re-treat the restenosis when it does occur, because that’s compared to bare-metal stents. That’s a really big deal.
Editor’s note: Dr. Ansel reports royalties from Cook Medical for non-Zilver PTX devices, as well as advisory board membership with Abbott Medical, W. L. Gore & Associates, Medtronic, Cardinal Health, and Boston Scientific.