Onyx ONE: Resolute Onyx as Good as BioFreedom in High-Bleeding-Risk Patients

Roxanne Nelson, RN, BSN

September 27, 2019

SAN FRANCISCO — A durable polymer-based drug-eluting stent was noninferior to a polymer-free drug-coated stent in patients at high-bleeding-risk on 1-month dual antiplatelet therapy (DAPT) after percutaneous coronary intervention, according to results of the Onyx ONE trial.

This is the first randomized trial to compare the Resolute Onyx (Medtronic) and the polymer-free BioFreedom (Biosensors) device in this patient population, said study author Stephan Windecker, MD, PhD, Swiss Cardiovascular Center, Bern, Switzerland. "These data demonstrate that Resolute Onyx is safe and effective in complex high-bleeding-risk patients who receive 1-month of DAPT," Windecker said.

The primary safety endpoint of cardiac death, myocardial infarction (MI), or definite/probable stent thrombosis at 1 year was 17.1% for Resolute and 16.9% for BioFreedom (risk difference, 0.2%; one-sided upper bound 95% CI, 3%; P for noninferiority = .011).

The study was funded by Medtronic. The late-breaking results were presented here at Transcatheter Cardiovascular Therapeutics (TCT) 2019.

Speaking during a press conference, panelist Marco Valgimigli, MD, PhD, University of Bern, Switzerland, noted that he doesn't think the study gives enough information about whether or not 1 month of DAPT is truly the optimal of balance safety and efficacy in this population.

"However, it answers another question, and that is if the physician decided that 1 month is the way to go, then this study, for the very first time, allows us to know that the Onyx stent is a very viable and reasonable option," he said.

Better Than Bare

Windecker noted that the LEADERS FREE trial, conducted in a European population at high bleeding risk on 1-month DAPT, showed the BioFreedom compared with a bare-metal stent had better 1-year efficacy and safety outcomes. The device has been commercially available in Europe since 2013 but is not available in the United States.

Results from the pivotal LEADERS FREE II, presented at TCT 2018, showed similar findings in patients treated in North America.

However, current generation polymer-based drug-eluting stents have not been compared with polymer-free drug-coated stents in patients at high bleeding risk treated with 1-month DAPT.

Resolute Onyx is a cobalt chromium stent with a core of platinum iridium for increased radiopacity and elutes zotarolimus over 180 days from a durable polymer known as BioLinx. The strut is thin at 81 μm in sizes 4.0 and smaller (91 μm in larger 4.5- and 5.0-mm diameters).

BioFreedom is a polymer- and carrier-free drug-coated stainless steel stent on a micro-structured surface on the abluminal side of the stent. Biolimus is contained without the use of a polymer and released over 28 days. The struts are relatively thick at 112 μm.

Comparable Results

Onyx ONE was a prospective, single-blind trial conducted at 84 global sites and randomly assigned 996 patients to Resolute or BioFreedom stents. Baseline and lesion characteristics were similar in both cohorts.

This was an elderly population with a high burden of diabetes in nearly 40% of patients, who also had high burden of previous MI and atrial fibrillation.

The mean number of high-bleeding-risk criteria was 1.6 per patient and 45.9% of patients met two or more criteria. The most common high-bleeding-risk features were in patients 75 years or older and users of oral anticoagulants.

One month after PCI, 92.5% of patients remained on DAPT, and at 2 months, 92% of patients were on single antiplatelet therapy, while at 1 year, 88% still remained on therapy. Single platelet therapy consisted of aspirin in 56% of patients and a P2Y12 inhibitor in 44%; and this remained consistent throughout the year.

Notably, crossover to the other study device was 4% in the BioFreedom group and 0.2% in the Onyx group (P < .001).

Post-procedure coronary angiography showed improved outcomes for Resolute Onyx compared to BioFreedom with respect to diameter stenosis and acute gain, which resulted in greater device success (92.8% vs 89.7%; P = .007).

Target lesion failure at 1 year was 18.0% for Resolute and 17.9% for BioFreedom (HR, 1.02; 95% CI, 0.83 - 1.26; P = .84). Bleeding rates were also similar in both groups.

Event rates for the primary safety endpoint were driven largely by MI; cardiac death was low and similar in both groups.

However, Windecker pointed out that although both arms were comparable, the rate of periprocedural MI was higher than anticipated but the rate of spontaneous MI was statistically higher in the Biofreedom arm (6.8% vs 4.3%).

There were no significant differences in early stent thrombosis, but the study was not powered for this outcome.

During discussion of the abstract, LEADERS FREE principal investigator Philip Urban MD, Hôpital de la Tour, Geneva, Switzerland, said, "We now have two very good stents; if we thought 1 month of DAPT is an appropriate choice, then either one is a good choice."

He did point out that the MI rate is higher in Onyx ONE than in LEADERS FREE, and questioned if it was peri-procedural.

Windecker explained that there was "rigorous ascertainment of MI." For example, not only were single troponin levels measured but serial ones were measured as well, he said, adding that the Onyx ONE study "just shows a difference in the methodology of MI ascertainment."

The study was funded by Medtronic. Windecker has disclosed institutional research grants from Abbott, Amgen, Bayer, Bristol Myers-Squibb, Boston Scientific, Biotronik, CSL Behring, Edwards Lifesciences, Medtronic, Polares, and Sinomed.

Transcatheter Cardiovascular Therapeutics (TCT) 2019. Presented September 26, 2019.

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