Novel SES Fails to Match Xience EES for Chronic Total Occlusions

WASHINGTON, DC—A novel hybrid sirolimus-eluting stent (SES) failed to meet noninferiority criteria compared with an established everolimus-eluting stent (EES) in successfully recanalized chronic total occlusions (CTOs), according to data from the randomized PRISON IV trial.

While the study did not meet its primary endpoint, it “raises the issue of how we define noninferiority,” said Ori Ben-Yehuda, MD (Cardiovascular Research Foundation, New York, NY), who was not involved in the study, in a media briefing at TCT 2016. “The results were so good” for both stents, he said, but the study population was too small at 330 patients to show any relevant comparability.

“Most DES trials are 1,000 patients,” added William Gray, MD (Main Line Health/Lankenau Heart Institute, Wynnewood, PA), also in the media briefing.

The SES in question (Osiro, Biotronik) has ultra-thin struts (60 µm) made of cobalt chromium covered with a silicon carbide layer of passive coating and a polymer designed to biodegrade within 12 months. Researchers led by Koen Teeuwen, MD (St. Antonius Hospital, Nieuwegein, the Netherlands), randomized 330 patients with successfully canalized CTOS to stenting with the SES or the gold-standard Xience EES (Abbott Vascular).

At 9 months, angiography data available on 281 patients did not show noninferiority for the SES compared with the EES in terms of in-segment late lumen loss (primary endpoint; 0.13 ± 0.63 vs 0.02 ± 0.47 mm; P for noninferiority = 0.11). In-stent late lumen loss was similar between the two stents (0.12 ± 0.59 vs 0.07 ± 0.46 mm; P = 0.52), but the incidences of both in-stent and in-segment binary restenosis were higher with SES (P = 0.028 for both) with comparable rates of reocclusions (2.2% vs 1.4%; P = 0.68).

Clinically-driven TLR at 12 months trended higher for patients treated with SES vs EES (9.2% versus 4.0%; P = 0.08), but there were no differences in MI, cardiac death, target vessel failure, definite or probable stent thrombosis, or MACE.

With the results as they stand, Teeuwen said he would still recommend the Xience stents for use in this patient group. That said, he still believes there are opportunities for manufacturers to “solely focus on treating CTOs” when developing new stents. “These are really different than de novo lesions,” Teeuwen added. “We need thin struts.”