WASHINGTON – The bioabsorbable vascular scaffold bubble suddenly burst with the first 3-year follow-up data from a randomized trial that unexpectedly showed that the Absorb device significantly underperformed compared with Xience, a widely-used, second-generation metallic drug-eluting stent.
“As a pioneer of BVS [bioresorbable vascular scaffold] I’m disappointed,” Patrick W. Serruys, MD, said at the Transcatheter Cardiovascular Therapeutics annual meeting. “The performance of the comparator stent was spectacular.”
Mitchel L. Zoler/Frontline Medical News
Dr. Patrick W. Serruys
Xience surpassed Absorb in several other secondary endpoints. For example, the in-device binary restenosis rate was 7.0% with Absorb and 0.7% with Xience; the in-segment binary restenosis rate was 8% with Absorb and 3% with Xience. Target-vessel MIs occurred in 7% of the Absorb patients and 1% of the Xience patients, while clinically indicated target-lesion revascularization occurred in 6% of the Absorb patients and 1% of the Xience patients.
Another notable finding was that definite or probable in-device thrombosis occurred in nine Absorb patents and in none of the Xience patients, a statistically significant difference. Six of the Absorb thrombotic events occurred more than 1 year after the device was placed, and in several instances these thromboses occurred more than 900 days after placement, when the BVS had largely resorbed.
“These thromboses are occurring at the late stages of BVS degradation,” Dr. Serruys noted. “The Absorb polymer is basically gone after 3 years, but it’s replaced by a proteoglycan, and some proteoglycans are quite thrombogenic,” a possible explanation for the “mysterious” very late thromboses, he said.
These “disappointing” results my be linked to inadequate lesion preparation, appropriate sizing of the BVS for the lesion, and inconsistent postdilatation of the BVS, three steps that became the guiding mantra for BVS use starting a couple of years ago, said Giulio G. Stefanini, MD, an interventional cardiologist at Humanitas Research Hospital in Milan and a discussant for the report at the meeting, which was sponsored by the Cardiovascular Research Foundation.
Dr. Giulio G. Stefanini
Dr. Stefanini said that even though the Absorb stent became available for routine use in Europe starting in 2012, the device gained little traction since then in his own practice and throughout Italy. Currently it’s used for fewer than 5% of coronary interventions in Italy, he estimated. That’s largely because “we have failed to identify a population that benefits.” Other issues include the extra time needed to place a BVS, and the need for longer treatment with dual antiplatelet therapy for patients who receive a BVS, compared with when they receive a modern metallic drug-eluting stent. The Absorb BVS received Food and Drug Administration approval for routine U.S. use in July 2016.
“It would be beautiful to have a fully bioresorbable stent. It’s a lovely concept, but we’re not there yet,” Dr. Stefanini observed.
ABSORB II was sponsored by Abbott Vascular, which markets the Absorb device. Dr. Serruys has received research support from Abbott Vascular and has been a consultant to several other device and drug companies. Dr. Stefanini has been a consultant to Boston Scientific, B.Braun, and Edwards.
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