SAN DIEGO – Seemingly nuanced differences between drug-eluting stents can translate to substantial differences in clinical outcomes longer term, updated results of the BIOFLOW V randomized trial reported at the Transcatheter Cardiovascular Therapeutics annual meeting suggest.
“As we have celebrated recently the 30th year of stent implantation, coronary drug-eluting stent development has included new metal alloys, changes in stent architecture, and bioresorbable polymers,” commented lead investigator, director of interventional cardiology and chief scientific officer at the Piedmont Heart Institute, Atlanta. “Yet whether these advancements improve long-term clinical safety and efficacy has been inconsistent in previous studies.”
BIOFLOW V compared the Orsiro ultrathin-strut, bioresorbable-polymer, sirolimus-eluting stent with the Xience thin-strut, durable-polymer, everolimus-eluting stent among 1,334 patients undergoing percutaneous coronary intervention.
Initial results showed that the primary outcome of 1-year target lesion failure – the composite of cardiac death, ischemia-driven target lesion revascularization, and target vessel–related myocardial infarction – was significantly lower in the Orsiro stent group (6% vs. 10%, P = .0399) (Lancet. 2017;390:1843-52). Superiority at this time point was mainly driven by a lower rate of target vessel–related MI (5% vs. 8%, P = .0155).
With the update, now at 2 years of follow-up, the significant difference in target lesion failure rate persisted, with a rate of 7.1% with Orsiro stents versus 11.9% with Xience stents (P = .015), according to results reported at the meeting and simultaneously published (J Am Coll Cardiol. 2018 Sep 19.).
There was likewise still a significant difference in favor of the Orsiro stent in target vessel–related MI, but the rate of ischemia-driven target lesion revascularization was now significantly lower as well. In addition, this stent yielded a lower rate of definite or probable stent thrombosis occurring late or very late.
“Altogether, these results not only advance a standard of comparison for new drug-eluting stents, but they direct our attention to strut thickness and polymer composition as key features for iterative drug-eluting stent development,” Dr. Kandzari summarized. Additional BIOFLOW V follow-up, out to 5 years, is planned, he noted.
Session comoderator, an interventional cardiologist at the Cardiovascular Institute at San Carlos University Hospital in Madrid, wondered about the role of dual-antiplatelet therapy. “Was that treatment related in some way to events? Was there any kind of interaction between those who were maintained on dual-antiplatelet therapy and those having late events?” he asked.
“Through 2 years of follow-up, adherence to dual-antiplatelet therapy was numerically identical in both groups. But it was not related in any way to either target vessel MI–related events or stent thrombosis events,” Dr. Kandzari replied.
The BIOFLOW V trialists recruited patients from 13 countries and enrolled those who had up to three de novo target lesions in up to two native target vessels. Patients were randomized 2:1 to receive Orsiro stents (Biotronik) or Xience stents (Abbott).
At 2 years, 45.6% of those in the former group and 45.1% of those in the latter group were adherent to dual antiplatelet therapy (P = .88), Dr. Kandzari reported at the meeting, which was sponsored by the Cardiovascular Research Foundation.
The lower 2-year rate of the primary composite outcome of target lesion failure with the Orsiro stent was driven by lower rates of both target vessel–related MI (5.3% vs. 9.5%, P = .01) and ischemia-driven target lesion revascularization (2.6% vs. 4.9%, P = .04). There was still no significant difference for cardiac death (0.6% vs. 0.5%, P = 1.0).
The edge of Orsiro stents over Xience stents for target lesion failure was similar across subgroups, with the possible exception of greater benefit of the latter in patients older than 75 (P for interaction = .039).
In landmark analyses, a significant difference in rates of target vessel–related MI favoring Orsiro stents was evident both in the first 30 days after the procedure (P = .04) and from 30 days to 2 years, presumably reflecting fewer spontaneous MIs (P = .01). Ischemia-driven target lesion revascularization did not difference in the first year of follow-up (P = .72) but it did between the first and second years (P = .01).
Most measures of stent thrombosis were similar for the two groups. However, the rate of definite or probable stent thrombosis occurring late or very late (between 30 days and 2 years) was just 0.1% for Orsiro stents, compared with 1.0% for Xience stents (P = .045).
Dr. Kandzari disclosed that he receives grant/research support from Biotronik, Boston Scientific, Medtronic CardioVascular, Medinol, and Orbus Neich, and that he receives consulting fees and honoraria from Biotronik, Boston Scientific Corporation, Cardinal Health, and Medtronic CardioVascular. The trial was sponsored by Biotronik.