Biodegradable polymer stent shows promise compared with Xience

Biodegradable polymer biolimus-eluting stents (Nobori, Terumo) are as safe and efficacious as the current standard of a thin-strut everolimus-eluting stent with a durable biocompatible polymer (Xience V or Prime, Abbott/Promus, Boston Scientific), according to a prospective, randomized, controlled COMPARE II trial.

The trial was published Jan. 30 in The Lancet.

To overcome unwanted late effects with hypersensitivity reactions and chronic inflammation in the vessel wall that might lead to late stent thrombosis with first-generation drug-eluting stents (DES), new DES platforms that make use of other rapamycin analogues and more biocompatible durable polymers or biodegradable polymers have been developed, according to the study authors.

One of these newer DES is the umirolimus (commonly known as biolimus)-eluting stent. This stainless steel stent (strut thickness of 120 um) is coated only at the abluminal site with a biodegradable polymer layer (20 um) that dissolves six to nine months after implantation and from which the lipophilic antiproliferative drug biolimus elutes.

The aim of the COMPARE II trial was to compare a biodegradable polymer-coated biolimus-eluting stent with a durable polymer-coated everolimus-eluting stent in patients undergoing PCI in clinical practice. This open-label, prospective, randomized, controlled, non-inferiority trial was conducted at 12 sites across Europe.

For the trial, Pieter Cornelis Smits, MD, of the department of cardiology at Maasstad Ziekenhuis in Rotterdam, Netherlands, and colleagues used limited exclusion criteria (older than 18 years, with a life expectancy of more than five years and a reference vessel diameter 2-4 mm) to enroll patients eligible for PCI. The researchers randomly allocated patients (2:1) by computer-generated random numbers to receive either a biodegradable polymer biolimus-eluting stent (Nobori) or a durable fluoropolymer-based everolimus-eluting stent (Xience V or Prime/Promus).

The primary endpoint was a composite of safety (cardiac death and non-fatal MI) and efficacy (clinically indicated target vessel revascularization) at 12 months, and they analyzed by intention to treat. Patients received dual antiplatelet therapy for 12 months after discharge.

From Jan. 12, 2009, to Feb. 7, 2011, Smits and colleagues enrolled 2,707 patients (4,025 lesions), 1,795 of whom were assigned to receive the biolimus-eluting stent (2,638 lesions) and 912 to an everolimus-eluting stent (1,387 lesions). Of these patients, 99.3 percent completed 12 months of follow-up.

Significantly more patients in the biolimus-eluting stent group received a non-assigned stent than did those in the everolimus-eluting stent group (5.9 vs. 2.1 percent). The primary endpoint occurred 5.2 percent in the biolimus-eluting stent group and 4.8 percent in the everolimus-eluting stent group at 12 months. The analysis per protocol did not change the outcome of this trial, according to the authors.

The researchers acknowledged that there is a need for longer follow-up to show whether the biolimus-eluting stent reduces the risk of stent thrombosis after one year when compared with the everolimus-eluting stent. Specifically, “[l]onger-term follow-up of the COMPARE II trial will show whether the beneficial effect of the biodegradable polymer biolimus-eluting stent on late stent thrombosis also applies when compared with newer-generation DES.”

Terumo Europe of Leuven, Belgium, and the Research Foundation of the cardiology department at Maasstad Hospital in Rotterdam, Netherlands, contributed funding for this trial.