Results presented at Transcatheter Cardiovascular Therapeutics conference; study shows risks, but researchers await longer-term results.

Cleveland Clinic researchers report that at three years, patients who received a type of dissolving coronary stent fared somewhat worse when compared to patients receiving drug-eluding metal stents, but researchers said the study’s results may not ultimately portray the potential for the stent’s future success.

The ABSORB III trial compared the Absorb everolimus-eluting bioresorbable vascular scaffold (BVS), which is designed to gradually dissolve over three years after being placed in a heart vessel, to the Xience everolimus-eluting stent (EES).

The trial enrolled 2,008 patients at 193 centers. Patients were randomized to either BVS (1,322) or a drug-eluting metallic stent (686 patients). The study’s primary endpoint was target lesion failure at one year, as measured by a composite of cardiac death, target lesion heart attack and ischemia-driven target lesion revascularization. That occurred in 7.7% of patients in the BVS arm compared to 6.0% of patients in the EES arm. By three years, event rates were 13.4% and 10.4%, respectively (P=0.056).

Researchers caution that there are two significant limitations to the data. First, the BVS was not expected to possibly be better than standard metallic stent until it fully reabsorbs, so longer term data are needed to fully access the merits of its use. These data will be forthcoming with the longer-term follow-up of the ABSORB III, as well as the more recent ABSORB IV, patients.

Second, BVS implantation technique has evolved and improved since the start of the trial. Evidence suggests that high pressure dilation of the vessel after implantation of the scaffold improves outcomes for BVS patients. However, at the initiation of the trial, this practice was not well-known and thus not consistently performed among study researchers.

“We don’t yet have the data to determine whether bioresorbable stents will be better for patients. Patients receiving coronary stents typically live 10-20 years after the procedure,” said Stephen Ellis, MD, of the Cleveland Clinic, who is a paid consultant for Abbott Vascular, which makes the Absorb BVS. “At three years, the stents have not fully dissolved, so we will have to wait for longer-term results. Admittedly, after early results accrued device use diminished. Other similar and more refined devices are under development.”

Dr. Ellis led the ABSORB III study along with Dean Kereiakes, MD, from Christ Hospital in Cincinnati.