Very Thin Strut Biodegradable Polymer DES Compared With Durable DES in BIO-RESORT Trial

October 30, 2016—Results of BIO-RESORT (TWENTE III), a large-scale, multicenter study found that treatment with two thin-strut drug-eluting stents were noninferior to a durable polymer drug-eluting stent and showed favorable clinical outcomes at 1 year in treating an all-comers population with a high proportion of patients with acute coronary syndromes. The data were presented at the TCT 2016, the 28th annual Transcatheter Cardiovascular Therapeutics scientific symposium in Washington, DC, and simultaneously published online by Prof. Clemens von Birgelen, MD, et al in The Lancet.

In the TCT press release, Prof. von Birgelen commented, “In patients with coronary artery disease treated with durable polymer-coated drug-eluting stents, the life-long presence of the polymer may delay arterial healing and even cause adverse clinical events. Biodegradable polymer stents might improve long-term outcomes, but studies with early biodegradable polymer stents that had thick stainless steel struts (120 µm) showed equivocal results. However, very thin-strut (60–81µm) biodegradable polymer stents that have flexible designs and thin, refined coatings are now available.” 

As summarized by TCT, BIO-RESORT was a large-scale, investigator-initiated, assessor- and patient-blinded, multicenter, three-arm trial that compared the safety and efficacy of two novel, very thin-strut biodegradable polymer stents to an established durable polymer stent (Resolute Integrity, Medtronic plc). 

According to the investigators, both biodegradable polymer stents have very thin struts but differ in the type, amount, distribution, and degradation speed of their respective coating. The Synergy everolimus-eluting platinum chromium stent (Boston Scientific) is the only biodegradable polymer drug-eluting stent approved by the US Food and Drug Administration for clinical use in the United States. This study was its first randomized assessment in an all-comers population. The Orsiro biodegradable polymer sirolimus-eluting cobalt chromium stent (Biotronik) has been used clinically outside the United States. 

In this study, patients were randomly assigned (1:1:1) to treatment with the very thin-strut biodegradable polymer everolimus-eluting or sirolimus-eluting stents or the durable polymer zotarolimus-eluting stent at four sites in the Netherlands. The study was composed of 3,514 patients. Of these, 2,449 (69.7%) patients had acute coronary syndromes, which included 1,073 (30.5%) ST-segment elevation myocardial infarctions. Twelve-month follow-up was available in 3,490 (99.3%) patients. 

The primary endpoint was a composite of safety (cardiac death or target vessel-related myocardial infarction) and efficacy (target-vessel revascularization) at 12 months, analyzed by intention-to-treat (noninferiority margin: 3.5%).

As summarized by TCT, the investigators reported that the primary endpoint was met by 4.7% (55/1,172) of patients assigned to everolimus-eluting stents, 4.7% (55/1,169) assigned to sirolimus-eluting stents, and 5.4% (63/1,173) assigned to zotarolimus-eluting stents. The noninferiority of the everolimus-eluting stent and the sirolimus-eluting stent was confirmed (both: -0.7% absolute risk difference, 95% confidence interval [CI], -2.4–1.1; upper limit of one-sided 95% CI, 0.8%, P_{noninferiority} < .0001). Definite stent thrombosis (ARC-defined) occurred in 0.3% (4/1,172), 0.3% (4/1,169) and 0.3% (3/1173) of patients, respectively (log-rank P = .7 for both main comparisons).

In the TCT announcement, Prof. von Birgelein concluded, “The 1-year results of BIO-RESORT show that treatment with two very thin-strut biodegradable polymer stents and the thin strut durable polymer zotarolimus-eluting stent was similarly efficacious and safe with excellent 1-year clinical outcomes in a complex population of all-comers.”