BIONYX Evaluates Medtronic's Resolute Onyx DES With Improved Radiographic Visibility

September 22, 2018—Findings from the BIONYX trial were reported at TCT 2018, the 30th annual Transcatheter Cardiovascular Therapeutics scientific symposium held September 22–25 in San Diego, California. The study was published simultaneously by Professor Clemens von Birgelen, MD, et al in The Lancet.

According to the TCT announcement, the BIONYX randomized clinical study of a polymer-coated zotarolimus-eluting stent (Resolute Onyx, Medtronic) that utilizes a novel thin-strut metallic platform allowing for better x-ray visibility compared to an ultra-thin-strutt bioresorbable polymer-coated sirolimus-eluting stent (Orsiro, Biotronik) that uses a cobalt-chromium strut platform. The study demonstrated that Resolute Onyx is noninferior to Orsiro.

The background of the study is that the Resolute Onyx stent was developed in response to the demand for stents with better radiographic visibility, which may facilitate the recognition of stents that are not yet well expanded or incompletely apposed to the arterial wall. The stent uses a novel thin-strut composite wire stent platform covered with a zotarolimus-eluting durable polymer coating. The metallic stent platform consists of a composite wire made from a dense platinum-iridium core, which makes the struts radiopaque, and an outer layer of cobalt-chromium alloy. The dense core also allows for a somewhat lower strut thickness. A head-to-head comparison with the Orsiro stent was of interest, as the Orsiro has shown excellent efficacy and safety outcomes in multiple randomized clinical trials, including three large-scale trials in all-comers.

As summarized by TCT, the intention-to-treat analysis included a total of 2,488 all-comer patients between October 7, 2015, and December 23, 2016. The patients were between 30 and 96 years of age, 594 (23.9%) were women, 1,765 (70.9%) presented with an acute coronary syndrome, and 1,275 (51.2%) were treated for an acute myocardial infarction at the time of study enrollment.

At 1-year follow-up, the primary endpoint of target vessel failure was met by 55 (4.5%) of 1,243 patients assigned to Resolute Onyx and by 58 (4.7%) of 1,245 assigned to Orsiro. Noninferiority of Resolute Onyx versus Orsiro was established with an absolute risk difference of -0.2% (95% confidence interval [CI], -1.9 to 1.4) and an upper limit of the one-sided 95% CI of 1.1% (P_{noninferiority} = .0005; P_superiority = .77).

The rates of cardiac death, target vessel–related myocardial infarction, and clinically indicated target vessel revascularization were low and similar in both groups. Definite or probable stent thrombosis occurred in a single patient (0.1%) in the Resolute Onyx group and nine patients (0.7%) in the Orsiro group (hazard ratio, 0.11; 95% CI, 0.01–0.87; P = .0112).

In the TCT announcement, Prof. von Birgelen commented, “The vast majority of contemporary stents use stent platforms from cobalt-chromium alloy which allows for the creation of fine mesh tubes with satisfactory radial force, but limited x-ray visibility. Suboptimal radiographic visibility can be challenging in obese patients, when treating bifurcated or calcified coronary lesions, or when carefully assessing stent expansion.” Prof. von Birgelen is an interventional cardiologist at Thoraxcentrum Twente and Professor of Interventional Cardiology at the University of Twente in Enschede, The Netherlands.

Prof. von Birgelen added, “Despite the difference in stent strut materials and thicknesses and the dissimilar durable and bioresorbable polymer coatings of the two study stents, the BIONYX study found no advantage for one stent over the other. Treatment with both stents was similarly safe and effective with excellent 1-year clinical outcomes in a complex all-comer patient population. The observed very low stent thrombosis rate in Resolute Onyx warrants further clinical investigation.”