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SAN DIEGO -- The bioresorbable-polymer Orsiro stent continued to outperform the durable-polymer Xience in randomized data going out almost 2 years.

Patients who got the Orsiro in the BIOFLOW V trial had target lesion failure occur among 7.5% at 720 days (vs 11.9% of Xience recipients, P=0.015), according to a presentation by David Kandzari, MD, of Piedmont Heart Institute in Atlanta, at the Transcatheter Cardiovascular Therapeutics conference.

The individual components of this endpoint suggest that this difference was mainly driven by MI:

• Target vessel MI: 5.3% vs 9.5% (P=0.007)
• Cardiac death: 0.6% vs 0.5% (P=1.000)
• Clinically-driven target lesion revascularization: 2.6% vs 4.9% (P=0.042)

Over the entire 720-day study period, stent thrombosis rates were similar between Orsiro and Xience groups. However, late and very late instances were more likely with Xience (0.1% vs 1.0%, P=0.045).

The BIOFLOW V investigators had randomized 1,334 patients to the Orsiro or Xience stents (in a 2:1 ratio). The former is a bioresorbable-polymer sirolimus-eluting stent featuring 60-μm struts; the latter a durable-polymer everolimus-eluting device with 81-μm struts. The two study arms were comparable at baseline.

"To the best of my knowledge, this is the only study showing , with many other, even bigger, studies showing comparable outcomes and even rates," commented Marco Valgimigli, MD, PhD, of the Inselspital Universitätsspital Bern in Switzerland, who was not involved in the study.

"I think this study does show that Orsiro is a good stent, and a good treatment option for our patients, but I am not personally convinced the superiority shown here is reproducible in other contexts," Valgimigli said, explaining that the probability that a single study shows unexpected and non-reproducible findings is "not small" and cautioning against claiming "real superiority out of study which was not designed to show this."

The new data mirror what was seen at 1 year in the trial, which appeared to show that Orsiro was better for preventing target lesion failure and target vessel-related MI.

These 1-year patterns were observed again in a separate subgroup analysis of patients with acute coronary syndrome (ACS), who made up half of the total BIOFLOW V cohort.

Patients who got stenting for ACS had 12-month target lesion failure rates of 5.6% and 11.0% with the Orsiro and Xience stents, respectively (P=0.02), according to Ariel Roguin, MD, PhD, of Rambam Medical Center in Haifa, Israel, and colleagues from their in Circulation: Cardiovascular Interventions.

The ACS cohort too showed a significant advantage in target vessel-related MIs after Orsiro placement in particular (no difference between groups being observed in cardiac death or target lesion revascularization). Their rate of spontaneous target vessel MI also favored this device (0.5% Orsiro vs 2.4% Xience, P=0.041).

As for stent thrombosis, neither group held the advantage at 1 year (0.5% vs 1.0%, P=0.601).

"Given that most of the difference in the present analysis between the stents was acute, it is unlikely to be because of the polymer coating or medications. It is thus possible that the difference in strut thickness could be responsible," suggested Roguin's group.

"The stent industry continues to try and improve on the second-generation DES [drug-eluting stent] technology by reducing strut thickness and composition, introducing bioresorbable polymer-based DES, polymer-free DES, and bioresorbable scaffolds. In general, the clinical outcomes with these newer technologies have at best been noninferior," the authors stated.

For now, "the amount of data clearly supporting the efficacy and safety of Xience is remarkable and perhaps this is today the stent with the highest amount of supporting evidence," according to Valgimigli.

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