TCT 2016: Very thin strut drug-eluting stents are non-inferior to durable polymer stent

After a year, patients who were implanted with either one of two very thin strut drug-eluting stents had similar safety and efficacy outcomes compared with those who received a durable polymer stent, according to a randomized, all-comers trial.

Lead researcher Clemens von Birgelen, MD, PhD, presented the findings Oct. 30 in a late-breaking clinical trials session at the Transcatheter Cardiovascular Therapeutics scientific symposium in Washington, D.C. Results of the trial were simultaneously published online in The Lancet.

The trial compared the Synergy everolimus-eluting platinum chromium stent (Boston Scientific) and the Orsiro sirolimus-eluting cobalt chromium stent (Biotronik) with the Resolute Integrity durable polymer zotarolimus-eluting stent (Medtronic). The three companies funded the study, but the researchers mentioned that the companies had no role in study design, data collection, data analysis, data interpretation or writing of the journal article.

The FDA approved the Resolute Integrity in February 2012 and the Synergy in October 2015. The Synergy is the first FDA-approved bioabsorbable polymer drug-eluting stent system. The FDA has not approved the Orsiro.

The Synergy has 74 μm, 79 μm or 81 μm platinum chromium struts, the Orsiro has 60 μm or 80 μm cobalt chromium struts and the Resolute Integrity has 91 μm cobalt chromium struts.

In this study, known as BIO-RESORT, the researchers enrolled 3,514 patients at four clinical sites in the Netherlands from Dec. 21, 2012, to Aug. 24, 2015. The patients were at least 18 years old and required a PCI with drug-eluting stent implantation. Of the patients, 70 percent had acute coronary syndromes and 31 percent had ST-elevation MIs.

The patients were randomized in a 1:1:1 ratio to undergo implantation with the Synergy, Orsiro or Resolute Integrity stents. Most patients also were prescribed dual antiplatelet therapy for 6 to 12 months.

At one year, 5 percent of patients in each group had met the primary endpoint, which was a composite of cardiac death or target vessel-related MI and target vessel revascularization. In addition, definite stent thrombosis occurred in 0.3 percent of patients in each group. The one-year rate of definite or probable stent thrombosis was similar between the groups, as well.

“The one-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 one-year clinical outcomes in a complex population of all-comers,” von Birgelen said in a news release. “The absence of a loss of one-year safety and efficacy with the use of these biodegradable polymer-coated stents is a prerequisite before assessing their potential longer-term benefits.”

The researchers acknowledged the study had a few limitations, including that the event proportion of target vessel failure was lower than expected. They also mentioned they could have under-reported adverse events.

“Although the present trial is a large-scale study, it is not powered to reliably assess very rare adverse clinical events, for instance, stent thrombosis,” the researchers wrote. “However, stent thrombosis is an event that is too important to be ignored, in particular as one of the two novel stents was never before assessed in an all-comers trial. These data are no more than hypothesis generating. Future studies might assess the potential of novel biodegradable polymer stents to be treated with short-term [dual antiplatelet therapy].”