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FDA panel supports approval of bioresorbable vascular scaffold
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The FDA’s Circulatory System Devices Panel recommended that a bioresorbable vascular scaffold should be approved for use in PCI for patients with ischemic heart disease.
The panel voted 9-1 that the bioresorbable vascular scaffold (BVS; Absorb GT1, Abbott Vascular) is safe, 10-0 that it is effective and 9-0 with one abstention that its benefits outweigh its risks.
Abbott Vascular is seeking approval for an indication for improving coronary luminal diameter in patients who have ischemic heart disease due to de novo coronary artery lesions at least 24 mm in length and who have a reference vessel diameter of 2.5 mm to 3.75 mm.
Breakthrough technology
“This is a breakthrough novel technology for patients undergoing PCI,” panel member Ralph G. Brindis, MD, MPH, from Oakland Kaiser Medical Center, San Francisco, who voted yes on all three questions, said during the meeting. “A rational and judicious case selection and procedural management through physician education will be key to ensure safety and efficacy.”
If approved, the BVS would be the first fully bioabsorbable device to treat coronary lesions on the U.S. market. The FDA approved a bioabsorbable polymer drug-eluting stent (Synergy, Boston Scientific), which has a bioabsorbable polymer with a metallic base, in October 2015.
“I think we better understand this [device] than many things we have been very enthusiastic about in the past,” said panelist George W. Vetrovec, MD, from the Virginia Commonwealth University Pauley Heart Center and Cardiology Today Editorial Board member, who voted yes for all three questions. “It’s certainly better studied. That gives me a lot of comfort.”
George W. Vetrovec
Abbott Vascular is seeking approval based primarily on the results of the ABSORB III trial. Results of that trial demonstrated that the BVS was noninferior to an everolimus-eluting stent (EES; Xience, Abbott Vascular) for the primary endpoint of target lesion failure at 1 year (BVS, 7.8%; EES, 6.1%; absolute difference, 1.7%). The upper bound of the 95% CI for the absolute difference in 1-year TLF was 3.93%, less than the prespecified noninferiority margin of 4.5%, according to briefing documents prepared by FDA staff. However, according to the documents, rates of cardiac death, target vessel MI and ischemia-driven target lesion revascularization were numerically higher in the BVS group than in the EES group at 1 year, and the rate of definite or probable stent thrombosis was more than twice as high for BVS at 1 year (1.54% vs. 0.74%; P = .13).
Panel member Warren K. Laskey, MD, from the University of New Mexico School of Medicine, Albuquerque, said he voted no on the safety question because he had “some difficulty with the noninferiority study design and a composite endpoint with components going in a way that was not expected.” He said he voted yes on the other questions because he otherwise “felt comfortable with the decision-making.”
Focus on vessel diameter
The event rates associated with BVS were highest in those with reference vessel diameters < 2.25 mm, which are not covered in the indication, according to the FDA briefing document.
“For optimal angiographic and clinical outcomes with BVS use, appropriate vessel selection, pre-scaffold implantation lesion preparation, and (possibly) post-dilatation, appear to be particularly important,” according to the FDA documents.
The panel members agreed, suggesting that the product not be used in patients with vessel diameters < 2.5 mm, that imaging studies verifying vessel diameter be completed before implantation and that post-dilatation with a noncompliant balloon be strongly recommended.
If the device is approved, Abbott has agreed to conduct a postapproval registry of 2,000 to 3,000 patients with 5-year follow-up. “The study will be designed to evaluate low frequency events, effectiveness of labeling, education for very small vessels (< 2.5 mm), and confirm generalizability of the treatment with the BVS to real-world practice,” the FDA staff wrote.
The FDA is not required to follow the recommendations of its advisory panels, but it usually does. – by Erik Swain
Reference:
Circulatory System Devices Panel Clinical Briefing Document. PMA P150023.
Disclosure: The members of the Circulatory System Devices Panel report no relevant financial disclosures.
Editor’s Note: On March 16, 2016, this article was updated with additional quotes and perspective.
Perspective
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Frederick Welt, MD, FACC, FSCAI
I definitely expected that this device would be supported by the panel. The idea of a bioabsorbable stent is such a compelling notion and such a feat of engineering, that given the results of ABSORB III, even with the concerns raised, I fully expected that people would want to see this technology brought forward.
In terms of efficacy, everyone [on the panel] thought it was equivalent enough. The real issue comes in safety, which was acknowledged. The critical concerns raised were about risk for stent thrombosis related to small vessel size, and also that the technique for implantation is going to have to be substantially more carefully done than with current metallic stents in terms of lesion preparation. This includes making sure that the BVS, which doesn’t have quite the same properties as a DES, goes in in a way that you can get complete apposition and a satisfactory result.
I don’t know how widely used the device will be if approved. The question that comes up is: Who is the right patient to get it? This is something I struggle with, because the benefit of having a stent that goes away eventually, while an interesting and appealing idea, is completely theoretical. Nothing that we’ve seen so far suggests that a stent that completely goes away will necessarily give some sort of advantage down the road. Everything that has been discussed, including more normal anatomy and return of normal vasomotion, is down the road. In discussions with colleagues over who is best suited for this, the best guess is younger patients, because maybe they will enjoy the benefits of a longer duration with an artery without a metallic stent. That has to be balanced with what risks have been reported, including numerically small but higher rates of early stent thrombosis, so it may be best for younger patients with easily accessible lesions and larger arteries. For me, personally, my thought is to use this in a minority of current patients. There may be patients who have heard about this and want it, because it’s such an appealing notion. But it is not clear how we will adopt this technology.
When the device is rolled out, we must make sure that interventionalists understand that it’s going to take a lot more care to place these, and the rollout must not occur in a way that results in increased risk for patients. When DES first came out, despite that risk that was seen early on after their arrival, the benefits were immediate and clear to everybody. We dramatically reduced restenosis rates and clinical events. Here, we have a new technology whose potential benefits we don’t even know yet, so I don’t know exactly how to use it right now.
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