A biodegradable drug-eluting stent (DES) proved to be noninferior to durable-polymer DES and both showed benefits over bare-metal stents (BMS) in the BASKET-PROVE II clinical trial. The results published online Nov. 19 in Circulation also raise questions about triggers for late complications.

Christoph Kaiser, MD, of the University Hospital Base in Switzerland, and colleagues provided two-year results from BASKET-PROVE II, a multicenter controlled, randomized clinical trial that compared three best-in-class stent types in patients with stable and acute coronary disease and STEMI who were in need of stents 3 mm or more in diameter. The trial’s two-year analysis was designed to assess long-term efficacy and safety of these stents in patients who receive the more potent antithrombotic agent prasugrel (Effient, Daiichi Sankyo) as a component of dual antiplatelet therapy.

The primary endpoint was major adverse cardiac events, defined as the combination of cardiac death, nonfatal MI or clinically driven non-MI-related target vessel revascularization, within two years. The safety endpoint was the combination of definite or probable stent thrombosis, MI or cardiac death.

BASKET-PROVE II enrolled 2,897 patients between 2010 and 2012, randomized equally to one of the three stent groups. The stents selected for the trial included the Nobori biolimus A9-eluting biodegradable-polymer DES (Terumo), the Xience Prime second-generation everolimus-eluting durable-polymer DES (Abbott Vascular) and the ProKinetik newest-generation thin-strut BMS (Biotronik). All stent patient groups had similar baseline characteristics.

At two years, the rate of the primary endpoint was 7.6 percent in the biodegradable DES group, 6.8 percent in the durable-polymer DES group and 12.7 percent in the BMS group.

Kaiser et al determined that the biodegradable DES was noninferior to durable-polymer DES after two years in an intention-to-treat analysis but noninferiority was not significant in a per-protocol analysis. The biodegradable DES was superior to BMS after two years, mostly due to the difference in non-MI-related target vessel revascularization. The combined safety endpoint was similar for the three groups.

They found that the durable-polymer DES was also superior to BMS at two years. Compared with the other stents, after the first year the biodegradable DES did not reduce the rate of very late stent thrombosis, MI or cardiac death. They pointed out that occurrence of stent thrombosis in the trial was low, possibly because of the use of prasugrel.

“The similar efficacy of biodegradable compared with current durable-polymer DESs during the initial year after stent implantation found here and in previous trials reflect similar antiproliferative efficacy of the different ‘-limus’ drugs,” they wrote. “In addition, the lack of an improved late safety (ie, the lack of a reduction of VLST [very late stent thrombosis] with biodegradable-polymer compared to best-in-class durable-polymer drug-eluting stents) observed here, seems to question the concept that durable polymers are key in late stent thrombosis formation.”

The results were also were presented Nov. 19 as a late-breaking clinical trial at the American Heart Association scientific session in Chicago.

For more information on biodegradable platforms, please read “Disappearing Act: From Coatings to Cage-free Coronaries.”