Trials Explore the Potential of Biodegradable-Polymer Stents

PARIS, France—Two trials conducted in all-comers populations provide new information on how DES equipped with a biodegradable polymer might benefit patients. The data were presented on May 19, 2015, at EuroPCR.

Final 3-year results of NEXT showed that newer technology offers outcomes comparable to those of a permanent-polymer DES but, on the other hand, does not seem to hold any long-term advantage. In addition, SORT OUT VII pitted 1 biodegradable DES against another, finding them largely similar.

Biodegradable vs Durable-Polymer DES

For the NEXT trial, Masahiro Natsuaki, MD, of Saiseikai Fukuoka General Hospital (Fukuoka, Japan), and colleagues enrolled 3,235 patients (mean age 69 years; 77% men) without exclusion criteria. Patients scheduled for DES implantation were randomized to receive the Nobori biodegradeable-polymer biolimus-eluting stent (BES; Terumo) or Xience/Promus durable-polymer everolimus-eluting stent (EES; Abbott Vascular/Boston Scientific). Three-year follow-up data were available for 97.6% of the cohort.

At 3 years, the BES was noninferior to the EES for the primary safety endpoint of death/MI.  Rates of TLR, the primary efficacy endpoint, also were similar between the 2 devices (table 1). Additionally, other clinical outcomes including death, cardiac death, MI, stent thrombosis, stroke, and TVR did not differ by treatment arm.

Landmark analysis confirmed that the 2 devices were associated with similar risks of death/MI, TLR, and definite stent thrombosis between years 1 and 3.

“There was no apparent signal suggesting either improvement or impairment of clinical outcomes with biodegradable-polymer biolimus-eluting stents compared with durable-polymer everolimus-eluting stents,” Dr. Nasuaki concluded, noting that 10-year follow-up is planned to observe any potential long-term benefits with the BES.

Panel member Pieter C. Smits, MD, PhD, of Maasstad Hospital (Rotterdam, the Netherlands), noted that this is the largest study yet to look at these specific devices. He asked for clarification on the “remarkably low” stent thrombosis rate of 0.3% in both groups at 3 years.

Dr. Natsuaki replied that the population is relatively low risk, with only 5% presenting with acute MI. Patients in Asia also have been shown to have lower stent thrombosis rates than those in Western countries, he said. Moreover, 80% of patients in NEXT underwent IVUS-guided PCI.

Head-to-Head Comparison of Biodegradable-Polymer DES

During the same session, Lisette Okkels Jensen, MD, DMSci, PhD, of Odense University Hospital (Odense, Denmark), presented data from SORT OUT VII.

Biodegradable-polymer DES were designed to improve safety and efficacy over existing DES, whose persistent polymers may trigger a chronic inflammatory response, Dr. Jensen explained. These “third-generation” devices have ultra thin struts, she said, and may further improve outcomes.

For SORT OUT VII, Dr. Jensen and colleagues randomly assigned 2,525 patients with chronic stable CAD or ACS to receive 1 of 2 types of biodegradable-polymer DES:

• Thin-strut, cobalt chromium Osiro sirolimus-eluting stent (SES; Biotronik)
• Stainless steel Nobori BES

Baseline lesion and patient characteristics were well matched between groups apart from a slightly higher mean age among SES-treated patients (66.1 vs 64.8 years; P < .01).

At 12 months, the SES met noninferiority criteria compared with the BES for the primary endpoint of target lesion failure (TLF; cardiac death, index lesion-related MI, or TLR). Each of the individual components also were similar between the 2 devices. Notably, however, the rate of definite stent thrombosis was lower in the SES group (table 2).

The difference in stent thrombosis “was mainly seen in the first 30 days,” Dr. Jensen noted.

Panel member Giulio G. Stefanini, MD, of Bern University Hospital (Bern, Switzerland), asked Dr. Jensen about mechanisms that could explain the disparity in stent thrombosis.

Emphasizing that the endpoint was secondary, Dr. Jensen suggested that strut thickness, polymer degradation time, and drug release time all could be factors in the difference. “[It is possible] that a drug-eluting stent with a biodegradable polymer is not necessarily a class effect,” she stressed. “There may be differences within that group.” Longer-term follow-up may provide some answers, she added.

Regardless, noted session chair William Wijns, MD, PhD, of Cardiovascular Center Aalst (Aalst, Belgium), “the good news is that the overall event rates [were] even lower than anticipated in your sample size calculation.”

1. Jensen LO. Randomized comparison of a sirolimus-eluting stent with a biolimus-eluting stent in patients treated with PCI: the SORT OUT VII trial. Presented at: EuroPCR; May 19, 2015; Paris, France.
2. Natsuaki M. Final three-year outcome of a randomized trial comparing second generation drug-eluting stents using either biodegradable polymer or durable polymer: the NOBORI biolimus-eluting versus XIENCE/PROMUS everolimus-eluting stent trial (NEXT). Presented at: EuroPCR; May 19, 2015; Paris, France.

Disclosures:

• NEXT was sponsored by Terumo.
• Dr. Jensen reports receiving honoraria from Abbott Vascular, AstraZeneca, Biotronik, and St. Jude Medical and institutional grant/research support from Biosensors International, Biotronik, St. Jude Medical, and Terumo.
• Dr. Natsuaki reports no relevant conflicts of interest.

Related Stories:

• NEXT at 2 Years: Nobori DES Still Noninferior to Xience/Promus
• Nobori BES Demonstrates Good Long-term Outcomes with No Stent Thrombosis Beyond 3 Years
• Trials Take on Permanent- vs. Biodegradable-Polymer Technology