BIOFLOW V: ‘Ultrathin-Strut’ Stent Beats Out Xience at 12 Months

BARCELONA, Spain—Among all the big trials airing results at the European Society of Cardiology (ESC) Congress 2017, one tiny stent—and its performance—could have slipped through the cracks. Earlier this week, 12-month results from the BIOFLOW V trial showed that the Orsiro “ultrathin-strut” coronary stent (Biotronik) had bested the market-leading Xience stent for both 12-month target lesion failure and MI.

The findings “advance a new standard,” according to lead investigator David Kandzari, MD (Piedmont Heart Institute, Atlanta, GA), who presented the findings here. BIOFLOW V was published simultaneously online in the Lancet.

It’s at least a decade since metallic drug-eluting stents were the headliners at the ESC Congress, but as Kandzari pointed out, the 60-µm stent, which incorporates a bioresorbable polymer that elutes sirolimus, has accomplished something that other market-approved devices have not.

“This is the first head-to-head, randomized comparison trial to show superiority over the Xience stent, which has been the benchmark for comparisons not only of novel drug-eluting stents, but also bioresorbable stents as well,” Kandzari told TCTMD. Other devices, he noted, have received approval on the basis of demonstrating noninferiority—and indeed, BIOFLOW V was designed as a noninferiority trial. But in post-hoc analyses, Orsiro was shown to also have met the cutoff for superiority.

BIOFLOW V is the US pivotal trial required to bring the device to the American market, where three manufacturers—Abbott, Boston Scientific, and Medtronic—are the only players in the field.

The trial randomized 1,334 patients 2:1 to Orsiro or Xience. Follow-up in both arms was approximately 97% at 12 months, at which time the primary endpoint, target-lesion failure, had occurred in 6.2% of the Orsiro-treated patients and in 9.6% of the Xience-treated patients (P =0.04).

Cardiac death and clinically driven TLR, both part of the primary composite, were no different between groups, but target-vessel MI was a key driver of the difference, occurring in 4.7% of the Orsiro patients and 8.3% of the Xience patients (P = 0.016). In a Bayesian pooled analysis that included patient-level data from both the BIOFLOW II and IV trials, yielding 1,466 Orsiro patients and 742 Xience-treated patients, the rate of target-lesion failure was 6.3% and 8.9%, respectively, a difference deemed significant in both noninferiority and superiority analyses.

Device Components

According to Kandzari, key differences between the Orsiro and the Xience are the drug (sirolimus versus everolimus), the polymer (bioresorbable versus permanent) and the strut thickness (60 µm, for the 2.25- to 3.0-mm diameter sizes, versus 81 µm).

The various components of the stent could be expected to be important at different time points, he observed. Thinness matters early for MI, drug efficacy contributes to low target-lesion restenosis later on, and polymer biocompatibility and dissolution could be expected to contribute to long-term safety.

“For the present findings, at least, of those three components, the most influential is perhaps the thinness of the stent strut,” Kandzari told TCTMD. On the Orsiro device, the bioresorbable polymer—an innovation intended to help with vessel-wall healing, leaving behind a clinically “inert” metallic stent—takes 24 months to fully degrade.

Commenting on BIOFLOW V for TCTMD, John P. Reilly, MD (Ochsner Medical Center, New Orleans, LA), agreed that interest in next-generation metallic stent news has flagged in recent years, particularly as hopes soared, then sunk, for the first-generation fully resorbable scaffolds.

The BIOFLOW V news, however, “deserves our attention,” he said. “This would be a new player to the US market, which we haven’t had in years.”

Reilly noted that the BioNIR RES (Medinol, Tel Aviv, Israel) is also poised to join the fray, following the positive BIONICS trial last year. “I think this is valuable from the point of view that we haven’t had a new vendor in the US in the drug-eluting stent space in a long time, and [Osiro] has better outcomes than we’ve seen before. So far, drug-eluting stents have been a commodity with very subtle differences between one and the other.”

The fact that BIOFLOW V showed noninferiority, but with a signal of better clinical outcomes and, in particular less MI, “will get the attention of interventional cardiologists,” Reilly predicted.

Where the “rubber hits the road,” however, will be when operators actually get the chance to try out the device. “That’s when people get to see whether they can actually see it or not when they’re implanting it, because it’s a thinner stent,” Reilly said. “Will it be deliverable? How much easier will it be to use? All of that we don’t know from this study.”