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Expert panel: Clinical need for bioresorbable technology remains
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Although disappointing data and safety issues hampered the introduction of bioresorbable vascular scaffolds, improvements in technology and implantation techniques as well as optimized patient selection and postprocedural management may help forge a place for these devices in PCI procedures, according to a consensus statement published in JACC: Cardiovascular Interventions.
“Because of the considerable amount of information, variability in practice and the number of statements being made regarding BVS, we convened a panel of experts to draft a consensus statement on the current strengths and limitations of BVS and what the future may hold,” lead consensus statement author Sripal Bangalore, MD, MHA, director of research, cardiac catheterization laboratory; director of the Cardiovascular Outcomes Group in the Leon H. Charney Division of Cardiology; and associate professor of medicine at New York University School of Medicine, told Cardiology Today’s Intervention.
Improved design
Despite early data that demonstrated safety and efficacy of the first FDA-approved BVS (Absorb, Abbott Vascular), longer-term follow-up has yielded less encouraging results, Bangalore and colleagues noted.
Specifically, 3-year data from ABSORB II showed that, when compared with the cobalt-chromium everolimus-eluting stent, the BVS did not meet its co-primary endpoint of superior vasomotor reactivity or noninferior late luminal loss. Target vessel-related MI and very late device thrombosis were also higher with BVS. Additionally, 2-year results from ABSORB III linked the BVS with higher rates of target lesion failure, and a meta-analysis of seven randomized controlled trials showed increased target vessel failure and worse safety outcomes with the BVS vs. EES at a median of 2 years. The BVS was also associated with higher target vessel-related MI, any MI, definite or probable device thrombosis and a low procedural success rate in the AIDA trial.
However, these increased adverse events are likely attributable to some of the limitations of the first-generation BVS, according to Bangalore.
When compared with DES, the BVS has thicker, wider struts, which can increase the risk for thrombosis, restenosis and periprocedural MI, as well as a higher crossing profile, which can lower the rate of procedural success, the panel noted in the consensus statement. Moreover, the device does not completely absorb until after 3 years, which can also increase the risk for adverse outcomes.
Therefore, making the device thinner and reducing absorption time may mitigate the risks associated with the current-generation BVS, Bangalore noted.
Goal to optimize outcomes
Although an improved scaffold design will help minimize the risk for adverse outcomes with BVS, it is only one piece of the puzzle, according to Bangalore.
“Another aspect is making the procedural aspects uniform — making sure that the BVS is used in the right patients and is implanted in the right way,” he said.
In the consensus statement, the expert panel points out that the BVS implantation technique, as with many new technologies, underwent a “learning curve.”
A strategy that involves adequate pre- and postdilatation and selecting the appropriate scaffold size can mitigate the adverse outcomes associated with the two most common technical issues: underexpansion and malapposition. Using imaging such as angiography, IVUS and optimal coherence tomography can also help guide proper sizing, according to the consensus statement.
“We believe a combination approach — improving the implantation technique and refining the technology to close the mechanical gaps between polymers and metal — will resolve the early and late thrombosis seen with poly-L-lactic acid based scaffold,” the panel wrote.
Appropriate patient and lesion selection is also essential to improving outcomes, as certain lesions may be better suited for BVS implantation, according to the panel.
Specifically, the consensus statement states that the device should not be used in vessels with a reference vessel diameter less than 2.5 mm because the thicker, wider struts of the current-generation BVS may increase the risk for scaffold thrombosis and restenosis in smaller vessels. Additionally, older patients, those who cannot take long-term dual antiplatelet therapy and those with highly calcified lesions are not good candidates for BVS implantation.
For ostial lesions, moderately calcified lesions and bifurcation lesions and in patients with ACS, clinicians should carefully weigh the risks and benefits to determine whether BVS implantation is appropriate, the panel noted.
The consensus statement also underscores the importance of postprocedural care in patients who undergo BVS implantation. The current recommendations reflect the recommendation made in clinical trials of continuing DAPT for 1 year. However, with data demonstrating an increase in very late scaffold thrombosis with BVS, the panel suggests that DAPT should perhaps be continued for longer than 1 year. Data from randomized controlled trials are not yet available for prolonged DAPT with BVS, but the panel noted that one observational study linked 18 months of DAPT with lower scaffold thrombosis compared with short-duration DAPT.
“Hopefully, making all of these changes, such as proper patient selection and appropriate use of DAPT, will improve outcomes with this kind of technology,” Bangalore said
Future of BRS technology
In March 2017, the FDA issued an advisory letter warning health care professionals about the potential for adverse outcomes with BVS. In September 2017, Abbott pulled the Absorb BVS device from the market due to low sales. These decisions, however, do not spell the end for this technology and should not hinder further development, according to Bangalore.
“There are many different iterations of the BVS, some of which are already much thinner, so hopefully we will see more studies of those devices,” he said. “Then we can see whether these technical improvements will actually provide comparable outcomes to current-generation stents.”
It is also important to remember that the issues seen with the introduction of BVS reflect previous experiences with new technologies and can potentially be resolved, Bangalore noted.
“We encountered problems with early-generation drug-eluting stents as well, but we persisted and improved the design, polymer-coating technology and more. Now, DES are considered even safer than bare-metal stents,” he said.
“Most interventional cardiologists agree that there is a need for a device like the BVS. Even with the latest generation of DES, there remains the risk for restenosis and the need for future revascularization in these patients. Therefore, we should not just give up on the BVS technology but continue its technical development and continue to conduct clinical trials so we can hopefully find a solution to the current problems we have with permanent metallic implants,” Bangalore told Cardiology Today’s Intervention. – by Melissa Foster
For more information:
Sripal Bangalore, MD, can be reached at sripalbangalore@gmail.com.
Disclosures: Bangalore reports he has received a research grant and honoraria from Abbott Vascular; has received travel grants from Boston Scientific and Medtronic; and has served on the advisory board for Abbott Vascular, Daiichi Sankyo, The Medicines Company and Pfizer. Please see the consensus statement for a full list of all other authors’ relevant financial disclosures.
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