Two-year data from the BIONYX trial show that all-comer patients who underwent percutaneous coronary intervention (PCI) with Resolute Onyx (Medtronic) had a similar rate of target vessel failure to those who underwent PCI with Orsiro (Biotronik). Additionally, unlike the earlier generation Resolute Integrity (also Medtronic), Resolute Onyx was not associated with poorer outcomes in patients with small vessels.
Rosaly A Buiten (Department of Cardiology, Thoraxcentrum, Medisch Spectrum Twente, Enschede, The Netherlands) and others write in JACC: Cardiovascular Interventions that the BIORESORT study found that a thin-strut, permanent polymer zotarolimus-eluting stent (Resolute Integrity, Medtronic) was associated with more repeat revascularisation than was the ultrathin-strut, biodegradable polymer sirolimus-eluting stent (Orsiro, Biotronik) for the management of patients with small vessels. The authors add that the next-generation Resolute Onyx, compared with Resolute Integrity, has a “refined design” and is based on “a thin metallic stent platform, made from a strut with an outer layer of cobalt-chromium alloy and a dense platinum-iridium core wire”. According to Buiten et al, these features allow “enhanced radiographic visibility” and ensure “reduced strut thickness while radial and longitudinal strength is maintained”.
Therefore, the aim of BIONYX was to assess how Resolute Onyx compares with Orsiro. Given one-year data from the study has already shown no significant differences in the rate of target vessel failure (the primary outcome) between the stents, the present analysis sought to look at longer-term data. Specifically, the authors planned to perform a subgroup analysis of the Resolute Onyx stent in patients with small vessels.
At two years, follow-up data were available for 2,460 patients. Of these, 1,243 had been randomised to receive Resolute Onyx and 1,245 had been randomised to receive Orsiro. There were no significant differences between groups in the rate of target vessel failure: 7.6% for Resolute Onyx versus 7.1% for Orsiro (p=0.66). Furthermore, there were also no significant differences in the individual components of target vessel failure (cardiac death, target vessel-related myocardial infarction, and clinically indicated target vessel revascularisation). The rate of stent thrombosis was low in both groups.
Regarding the prespecified subgroup analysis of patients with small vessels, Buiten et al report that 36.4% of patients (overall) were treated for at least one small vessel (<2.5mm). They write: “Between the zotarolimus-eluting stent and the sirolimus-eluting stent, there was no significant difference in the incidence of target vessel failure [8.2% vs. 8.7%; p=0.75] and target lesion revascularisation [4% vs. 4.4%, respectively; p=0.77].” The authors observe that the higher incidence of repeat revascularisation seen with Resolute Integrity in BIORESORT, that was not seen with Resolute Onyx, was “encouraging”.
Buiten told Cardiovascular News: “The results of the Resolute Onyx stent in BIONYX at two years are remarkable, given the fact that it competes with the Orsiro stent that has demonstrated in two previous clinical trials superiority versus another excellent drug-eluting stent.” In the paper, the authors explain that Orsiro has “demonstrated in two clinical trials superiority versus the cobalt-chromium fluoropolymer-coated everolimus-eluting Xience stent; a device for many years was considered the ‘gold-standard’ drug eluting stent”.
“At two-year follow-up, the novel thin composite wire strut durable polymer Resolute Onyx zotarolimus showed in all comers, excellent safety and efficacy, similar to that of the ultrathin cobalt-chromium strut biodegradable polymer Orsiro sirolimus-eluting stent,” they conclude.
In an accompanying commentary, Raffaele Piccolo and Giovanni Espositio (both University of Naples, Naples, Italy) write that the study supports the idea that there is a “class effect” for new-generation drug-eluting stents in terms of safety and efficacy. “In particular, it provides evidence that polymer biodegradability does not matter as long as a permanent polymer is highly compatible,” they add.