WASHINGTON – In the latest analysis of data from a randomized trial comparing three different thin polymer-coated drug-eluting stents, the signal at 1 year that the thinnest device might reduce risk of target lesion revascularization has been lost at 3 years, according to an update of results from the BIO-RESORT trial presented at CRT 2019 sponsored by MedStar Heart & Vascular Institute.
“At 3-year follow-up, all three drug-eluting stents were associated with favorable outcomes and both very thin strut polymer-coated devices showed safety and patency similar to the thin-strut durable polymer drug-eluting stent,” reported Clemons von Birgelen, MD, PhD, professor of cardiology, University of Twente, Enschede, the Netherlands.
In order of strut thickness, the stents tested in BIO-RESORT were Orsiro (60 mcm), Synergy (74 mcm), and Resolute Integrity (90 mcm). Although the study had a noninferiority design, the potential for the biodegradable polymer coatings of the two thinner stents to provide faster healing than the durable polymer of the Resolute stent was one of the driving hypotheses of the trial (Lancet. 2016 Nov 26;388:2607-17).
Some support for this hypothesis was provided by 2-year results presented at EuroPCR 2018 last year. At that time, it was reported that the risk of target lesion revascularization between the end of year 1 and end of year 2 was significantly lower for the Orsiro stent (1.3%) than the Resolute stent (2.3%). Target lesion revascularization also was lower in the Synergy stent group (1.8%), but this rate did not differ significantly from that of the other two stents in the trial.
Now, reassessed at 3 years, the target lesion revascularization rates are 2.9%, 3.3%, and 3.8% for the Orsiro, Synergy, and Resolute stents, respectively. Although the numerical hierarchy is preserved, the differences are no longer significant.
Other outcomes, including the primary outcome of target lesion failure, show the same numerical hierarchy but, again, without differences reaching significance. For target lesion failure, these rates are 8.5%, 8.8%, and 10.0%, respectively.
The difference in the rates of stent thrombosis at 3 years was even smaller with rates of less than 1% for all three stents. A catch-up phenomenon between years 2 and 3 of follow-up largely eliminated a numerical advantage seen earlier for the Orsiro stent.
The BIO-RESORT trial randomized 3,514 patients, of whom 70% had an acute coronary syndrome. Nearly one-third had an ST-elevated myocardial infarction. Dr. von Birgelen emphasized that this was “a very complex study population.” For example, roughly 20% had severely calcified lesions. Follow-up data were available on 97% of the randomized patients at 3 years.
There are differences between these stents other than thickness and the durability of the polymer. In particular, Orsiro is coated with sirolimus, Synergy with everolimus, and Resolute with zotarolimus. While the metals of the frame also differ, the estimated time to resorption of the polymer is faster with the Synergy stent (4 months) than the Orsiro stent (24 months).
Despite the loss of a difference in target vessel revascularization in the most recent follow-up, the potential for the differences in designs and materials to influence risk of late complications, including revascularization and thrombosis, persists.
“Follow-up beyond 3 years is of interest to definitely answer the question of whether one of these drug-eluting stents might improve outcome at a later stage,” Dr. von Birgelen said.