Editor's note: See a video clip from this interview.
At the 5th Annual Amputation Prevention Symposium, Vascular Disease Management spoke with Thomas Davis, MD, about the Endovascular Atherectomy Safety and Effectiveness (EASE) trial, an FDA-approved Investigational Device Exemption (IDE) clinical trial designed to evaluate the safety and effectiveness of the Phoenix Atherectomy catheter (Volcano Corporation), a minimally invasive device for the treatment of peripheral arterial disease (PAD) in the legs. Dr. Davis served as the national principal investigator for the trial.
VDM: Could you provide some background on the EASE trial and how it applies to therapies for critical limb ischemia (CLI)?
Davis: The EASE trial evaluated the Phoenix catheter, which is an over-the-wire atherectomy device that spins at about 1,200 revolutions per minute. The unique action of the Phoenix device is the mechanism of the Archimedes screw, which pulls back the plaque. The size of the device is 1.8 mm, so it’s ideal for popliteal arteries and below. It also shaves off the plaque in such a way that it does not send anything downstream.
VDM: What are some particular points of data that you think are remarkable?
Davis: I should point out that this was safety-driven data, because it was the IDE approval device. With that in mind, it was very remarkable that there were just over 100 patients and we did not use any filters at all. Angiographic core laboratory results showed only 1 evident distal embolization. So it does really remove the tissue very nicely and limits distal embolization. The other thing that’s remarkable about it is that you don’t have to predilate with it because it’s an end-hole cutter. We had just 1 patient who needed predilatation before the procedure. There were also very low complication rates for dissections, perforations, and so on.
VDM: Anything that surprised you and you didn’t expect to see?
Davis: The distal embolization rate did surprise me because for other atherectomy devices during the IDE trials, where they did not use filters or used them sparingly, there was 2% or 3% evidence of distal emboli. So having only 1 patient that had distal embolization over 100 patients was surprising in that context.
VDM: How do you think the data will change clinical decision making for vascular specialists?
Davis: It’s a very simple device to use and it’s very effective in popliteal below the knee arteries. However, I don’t want to pigeon-hole it as an exclusively below-the-knee device. In fact, about one-third of the patients in the trial were treated above the knee. Another benefit to clinicians is that it is a single-insertion device and doesn’t require any capital equipment. The setup is very easy. You place the catheter, you put the battery pack on, and you put it on the wire and go. We had very good results in the EASE trial with getting less than 50% residual stenosis after atherectomy.
VDM: Do you have a favorite patient case?
Davis: We included patients with Rutherford class IV and V disease. We had one patient who had a Rutherford V wound who had what I would consider to be a very difficult lesion to treat. We got a wire down in the very distal popliteal P3 segment going into the anterior tibial segment. We ran it though twice and we didn’t have to use any adjunctive therapy at all. We had anticipated having to use some adjunctive therapy and having it look pristine with good runoff was a nice surprise.
VDM: What else should vascular specialists know about the device and the data?
Davis: Because the data are safety driven it’s hard to say too much, but I think that it’s remarkable for its very low complication profile. Also, it was more than 90% effective at getting a residual stenosis of 50% or less. In terms of atherectomy, we’ve seen some data that indicate that if you are able to debulk a little bit more, closer to 70% even, using drug-coated balloons or drug therapy, you will probably get a better result. The Phoenix catheter is very efficient at debulking. Also, there will be a deflection sheath that the 2.2 mm catheter fits in, and it will be able to treat larger vessels – 4, 5, and potentially even 6 mm – more effectively, and because it is single-insertion, you can direct it and make it almost a directional rotational atherectomy. So realistically this is going to be the first and only rotational directional atherectomy on the market.
Thomas Davis, MD, is the Director of the Cardiac Catheterization Lab and the Director of Peripheral Interventions and Disease at St. John Hospital and Medical Center in St. Clair Shores, Michigan. Dr. Davis reports consultancy to and travel reimbursements from Philips and Volcano Corporation.