Abbott’s bioresorbable stent demonstrates efficacy and safety at three years
Abbott today announced that results from two randomized clinical studies of Absorb, the first fully-dissolving heart stent, showed comparable efficacy and safety to the leading drug-eluting stent XIENCE at three years. The data were presented in a late-breaking session at the annual EuroPCR Scientific Program in Paris, France.
"Three-year results from the ABSORB China and ABSORB Japan trials provide reassuring data about the longer-term efficacy and safety of Absorb," said Charles Simonton, M.D., chief medical officer for Abbott's vascular business. "There is a substantial growing body of evidence from physician experience around the world that demonstrate favorable short- and long-term clinical outcomes when current instructions for use are followed."
Results from the ABSORB China trial (n=475) showed that the previously presented two-year favorable efficacy and safety results for Absorb continued into three years. There were no new cases of stent thrombosis in either study arm between two and three years after treatment.
The ABSORB China study treated the highest number of appropriately-sized vessels among four randomized controlled trials (ABSORB China, ABSORB Japan, ABSORB II and ABSORB III).
Current implantation guidelines specify that Absorb should not be implanted in very small vessels (less than QCA 2.25mm).
Cumulatively at three years, rates of target lesion failure (TLF) were comparable between Absorb and XIENCE without statistically significant differences. Target lesion failure rates for Absorb were 5.5 percent vs. 4.7 percent for XIENCE (p=0.68). Rates for stent thrombosis were also not statistically significant at 0.9 percent for Absorb vs. 0.0 percent for XIENCE (p=0.50). There were a total of two cases of probable or definite stent thrombosis that occurred on days 15 and 622, respectively, with Absorb; post-dilatation was not performed in either case, as is now specified in contemporary implantation guidelines.
“In the ABSORB China study, Absorb has consistently demonstrated comparable safety and efficacy to XIENCE, and this trend continued from two to three years in all clinical endpoints," said Dr. Simonton. "Three-year results of the ABSORB China study supports that implanting Absorb in appropriately sized vessels positively affects patient outcomes."
Clinical outcomes from the ABSORB Japan trial (n=400) were comparable between Absorb and XIENCE arms, with no statistical difference in safety and efficacy at three years. Fourteen percent of vessels treated in the study would be considered too small according to today's standards for implantation of Absorb.
Safety events were similar for Absorb and XIENCE between years two and three, indicating that the risk of late adverse events with Absorb may remain low if early safety events can be avoided with current implantation technique. Target lesion failure rates in this timeframe were 1.6 percent for Absorb vs 1.6 percent for XIENCE (p=1.00). One stent thrombosis occurred in the Absorb arm between years two and three, at day 810; the scaffold was determined to be under expanded.
Due to higher event rates during the study's first two years -- which were previously presented at the European Society for Cardiology meeting in August 2016 -- cumulative three-year adverse events for Absorb were numerically higher than XIENCE though not statistically significant. At three years, target lesion failure rates were 8.9 percent for Absorb vs. 5.5 percent for XIENCE (p=0.23), and the rate of probable/definite stent thrombosis was 3.6 percent for Absorb vs 1.6 percent for XIENCE (p=0.35).
"Analyses of previous studies continue to reinforce that current implantation technique leads to good results." said Dr. Simonton. "The low event rates from years two to three in ABSORB Japan are reassuring, and indicate that if early safety events can be avoided by treating the right vessels and fully expanding the scaffold, the risk of additional events may remain low."
Thirty-day results of a more contemporary ongoing study (ABSORB IV) that started after implantation technique evolved are expected in the coming months. A preliminary analysis of pooled rates (combined for both Absorb and XIENCE because the study is not yet unblinded) showed stent thrombosis rates that were less than half of that observed in the U.S. pivotal trial.
Stent thrombosis rates in ABSORB IV were 0.4 percent at 30 days (N=2397) and 0.5 percent at one year (N=1415), compared to 0.9 percent at 30 days and 1.1 percent at one year in the pivotal ABSORB III study.
Abbott began studying Absorb in clinical trials in 2006. Training on the device has evolved over time based on physician experience. Analyses of clinical trials around the world demonstrate that when Absorb is implanted according to current specific instructions for use, outcomes are comparable to Abbott's XIENCE, the leading drug eluting stent, with stent thrombosis rates of less than 1 percent.
More information about Absorb including Important Safety Information is available at Absorb.com.
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