Data presented from ABSORB China and ABSORB Japan at EuroPCR (16–19 May, Paris, France) show the bioresorbable scaffold Absorb (Abbott Vascular) to have comparable safety and efficacy to an everolimus-eluting permanent metallic stent (Xience, Abbott Vascular) at three years. These findings are in contrast to those of the two-year results of ABSORB III, which showed target lesion failure to be higher with Absorb.
The results from the ABSORB China trial (n=475) showed that the previously presented two-year favourable 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. Additionally, a press release reports, the ABSORB China study treated the highest number of appropriately-sized vessels among four randomised 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).
Furthermore, 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% vs. 4.7% for Xience (p=0.68). Rates for stent thrombosis were also not statistically significant at 0.9% for Absorb vs. 0.0% 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.
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 per cent of vessels treated in the study would be considered too small according to today’s standards for implantation of Absorb.
The press release notes that safety events were similar for Absorb and Xience between years two and three, which it claims indicates 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% for Absorb vs. 1.6% 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 ABSORB Japan’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% for Absorb vs. 5.5% for Xience (p=0.23), and the rate of probable/definite stent thrombosis was 3.6% for Absorb vs. 1.6% for Xience (p=0.35).