FUTURE-II trial may indicate a comeback for absorbable stents, principal investigator says
A new generation of bioresorbable vascular scaffolds (BVS) with a thinner strut have 1-year safety and efficacy data comparable to cobalt-chromium everolimus-eluting stents (EES), according to new trial findings presented Tuesday at the EuroPCR conference.
Ten years ago, initial studies of BVS versus metallic drug-eluting stents showed some superiority in terms of vascular restoration therapy, with recovery of vasomotion and vascular pulsatility when the scaffold was absorbed, said co-principal investigator Bo Xu, MBBS, from the National Center for Cardiovascular Diseases at the Chinese Academy of Medical Sciences.
However, larger randomized clinical trials and subsequent meta-analysis – all powered to hard clinical endpoints – showed that BVS made of poly-lactic polymer displayed a higher rate of target lesion revascularization, and in particular a higher rate of scaffold thrombosis, when compared to metallic drug-eluting stents like cobalt-chromium everolimus-eluting stents – which led to BVS made of polylactic acid being withdrawn from the market, he noted.
Xu noted that although BVS use is limited nowadays, the need of a bioresorbable scaffold for treating coronary lesions, leaving nothing behind and allowing the so-called vascular restoration therapy, is still very much alive.
Xu presented late-breaking findings Tuesday from the FUTURE-II trial – a randomized trial comparing Firesorb (a new-generation thin-strut BVS made from poly-L-lactic acid) versus everolimus-eluting cobalt-chromium stent (EES).
The team found that the second-generation Firesorb scaffold (MicroPort, Shanghai)was comparable to the Xience EES (Abbott Vascular, Chicago) on a range of clinical and safety outcomes including late lumen loss at 1 year – a primary surrogate endpoint that is known to be associated with clinical event rates.
A total of 433 participants from 28 Chinese centers were randomized to receive either the Firesorb BVS (n=215) or EES (n=218). The primary endpoint was 1-year angiographic in-segment late loss (LL) powered for noninferiority testing, while the key secondary endpoint was 1-year proportion of covered struts assessed by optical coherence tomography (OCT) powered for noninferiority and subsequent superiority testing.
The trial reported the non-inferiority of Firesorb versus EES for 1-year angiographic late lumen loss (0.17 ± 0.27 vs. 0.19 ± 0.37 mm, p < 0.001), adding that no difference was found in terms of target lesion failure between groups with a very low rate of events (1.9% vs. 3.3%, p=0.37) and no definite probable device thromboses.
Non-inferiority was also shown in the secondary OCT endpoints, with a similar proportion of covered struts in both groups, and less incomplete strut apposition found in Firesorb versus EES group at 1 year, noted the team – adding that the latter finding may be the result of scaffold resorption.
The Chinese team noted that the implantation techniques used in BVS were related to adverse events rates – adding that the first-generation bioresorbable scaffolds were characterized by a thick strut of 150 microns, which made it similar to first-generation metallic DES “and therefore very much dependent by a very precise implantation technique.”
The second-generation Firesorb scaffold has a strut thickness of only 100-125 micron, making it close to second generation drug-eluting metallic stents, noted Xu.
He added that the results from the FUTURE-II trial may provide a new opportunity for the comeback of poly-lactic polymer-based BVS with improved physical and mechanical properties.