PRIZER study to put the spotlight back on bare metal stents


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Koen Deloose

Koen Deloose (Sint Blasius Hospital, Dendermonde, Belgium) talks to Interventional News about the importance of treating femoropopliteal disease patients and why some of the new generation bare metal stents are more advantageous for those complex lesions. He also discusses the PRIZER study, currently under enrolment, which aims to confirm the safety and efficacy of the Renzan peripheral stent system (Terumo Interventional Systems).

How prevalent is femoropopliteal disease and what is the impact of non-treatment for both patients and wider healthcare systems?

I think we are all aware of the fact that today the prevalence of peripheral arterial disease (PAD) in people over the age of 70 is around 15% and one out of every three of these definitely needs treatment. Interventional treatment can include supervised walking exercises as well as medicament therapy. My experience, and indeed my preference, is a combination of treatments. It is important for the patient that they are on the right drugs, that they are doing sufficient exercises but also that they are revascularised, whether with a bypass or, our preference, with a minimally invasive endovascular approach.

There are two categories of PAD patients—on one side you have the claudicants, and on the other the chronic limb-threatening ischaemia (CLTI) patients. We know that 5% of the severe claudicants are also evolving towards becoming CLTI patients. However, in a lot of countries they do not treat the claudicants with anything other than a conservative approach. In Belgium and in many other European countries we have noticed that there is definitely a space for the treatment of claudicants, especially as severe claudication has a very profound impact on the quality of life of the patient, and on their independent wellbeing.

These patients (Rutherford 4+) have rest pain or they have a lot of tissue loss and so if you stick to just a conservative approach these people are definitely going to end up with major amputation or death. Lack of treatment thus can have a huge impact on the social life of patients and ultimately a financial impact on healthcare systems as well. So we need to avoid this and we need to intervene, on time, in this category of patients.

How can the use of different stents to treat calcified lesions help resolve the unmet needs of these patients?

I noticed in my own practice in Dendermonde that the idea of ‘leaving nothing behind’ just did not work. It only worked for the straightforward, easy, non-calcified, stenotic, relatively short lesions, where it was feasible to treat these patients with angioplasty alone or a drug-coated balloon (DCB). But the vast majority of lesions that, as a vascular surgeon, I come across are chronic total occlusions. They tend to be more than 15cm TASC C and D severely calcified lesions. And so I noticed that the dream of leaving nothing behind remained a dream.

Because of this, in more than 50% of these patients, we need a scaffold. So I think there should be a greater focus on the need for bare metal stents, because a lot of interventionalists have almost forgotten the existence of bare metal stents. But in this category of patients, DCB alone or angioplasty alone is insufficient and we need bail-out scaffolding.

There are currently a wide range of stents available. For example, we have stents with very low chronic outward force that we use to scaffold a flow limiting dissection in the less calcified lesions. But then we also have the severely calcified lesions where we need bare metal stents with a very high radial resistive force and crush resistance such as the Renzan stent which is the new kid on the block. It is definitely important to select the right bare metal stent for the right indication and that is the challenge we need to overcome today.

How have stents evolved over time and why is it important to have next-generation stents like self-expandable micro-mesh stents available on the market?

In my mind and in my hands there are some essential requirements when it comes to the ideal bare metal stent. For me, as a pragmatic vascular surgeon, it first of all needs to be easy to use. If it is too complex, takes too many steps to implant, forget it. And of course accuracy of deployment. For example, if you really want to end up at the ostium of your superficial femoral artery for instance you need 100% accuracy. The nice thing about the Renzan stent is the fact that it is repositionable. So if you make a mistake, if you did not take into account tortuosity in the access towards the vessel and you made an error, you can reposition and try again.

When we are talking about the femoropopliteal area, visibility, flexibility, and conformability to the vessel anatomy are also extremely important. You need the right chronic outward or radial forces. I notice that especially in the USA, a lot of physicians are using distal embolic protection devices to avoid distal embolization. These definitely have some disadvantages, including additional steps to the procedure that come with their own potential difficulties and complications. However, we now have a bare metal stent available with dual layer micro mesh technology, which aims to prevent plague prolapse and distal embolization based on experience in other therapeutic areas.

Renzan peripheral stent system

What is the PRIZER study and what do you expect or hope to see?

The PRIZER study is a prospective multicentre post-market single-arm study which is looking to assess the performance of the Renzan stent in femoropopliteal disease treatment. There are two endpoints, a safety endpoint—defined as freedom from deaths, TLR and any amputation of the index limb at 30 days—and then we have an efficacy endpoint which is defined as primary patency at one year. We plan to enrol 135 patients in this study with follow-up of 36 months. There are 13 centres enrolling patients across five European countries: Germany, The Netherlands, Belgium, France and Spain.

I am actually excited about the spotlight again being on bare metal stents. I have mentioned that the dream of leaving nothing behind with a DCB has remained, in 2023, a dream, especially for the more complex lesions. On the other side of the spectrum if we are talking about drug-eluting stents, which have a lot of advantages but also some disadvantages such as the short lengths of some devices, so when treating a 30cm lesion I might need three stents which, in the Belgian healthcare system, is unpayable. There is also data showing signs that in the long run there can be some toxicity of paclitaxel.

On the other hand, we have access today to a completely new generation dual-layer micro-mesh stent that is repositionable with the right chronic outer force, radial resistive force and crush resistance. To ensure a proper stent deployment, it is important to respect some key aspects of the instructions for use and do an extensive vessel preparation before implanting the stent. There is also a learning curve that you need to overcome in order to be an expert at Renzan implantation.

I am happy about this device, and I hope that the PRIZER study with the Renzan stent will confirm my enthusiasm.

Disclaimer: The Renzan Peripheral Vascular Stent System is indicated for use in patients with Peripheral Vascular Disease. Refer to instructions for use, contraindications and warnings for additional information. Renzan is manufactured by MicroVention Europe and distributed by Terumo Europe N.V. All brand names are a Trademark or registered trademarks of TERUMO CORPORATION, its affiliates, or unrelated third parties.


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