Results from the BIOFLOW V study indicate that patients who undergo percutaneous coronary intervention (PCI) using a sirolimus-eluting stent with a biodegradable polymer (Orsiro, Biotronik) have a significantly lower rate of target lesion failure at 12 months than those who undergo PCI using an everolimus-eluting stent with a durable polymer (Xience, Abbott Vascular)—at present, Xience is considered to be the gold-standard device for PCI.
Presenting the study at the European Society of Cardiology (ESC) congress (26–30 August, Barcelona, Spain), David E Kandzari (Piedmont Heart Institute, Atlanta, USA) reported that the “persistence of adverse events” after PCI even with contemporary permanent polymer drug-eluting stents “presents an opportunity for iterative improvement”. He added that potential improvements to current devices include thinner struts, stent design modifications, and biodegradable polymers, noting: “Biodegradable polymers precisely control drug release while allowing simultaneous or subsequent dissolution of the polymer material, eliminating the stimulus for chronic inflammation and hypothetically restoring the stent phenotype to an inert bare metal stent.”
However, Kandzari commented that—to date—no study comparing biodegradable polymer devices with permanent polymer devices “has demonstrated a statistically meaningful difference in clinical outcomes” as only non-inferiority has been reported. Additionally, Kandzari observed that previous randomised controlled trials that have compared Orsiro—which he described as an “ultra-thin” (60 μm stent strut thickness), biodegradable polymer device—with the gold-standard permanent polymer, drug-eluting stent Xience (BIOFLOW II to BIO-RESORT) have “varied considerably” in terms of size, primary endpoint, and patient population. Therefore, the aim of BIOFLOW V was to further compare the clinical outcomes of Orsiro with those of Xience in a broad patient population.
In BIOFLOW V, patients with stable angina, unstable angina, or silent ischaemia were randomised to undergo PCI with Orsiro (884) or with Xience (450). The primary endpoint was target lesion failure—a composite of cardiovascular death, target vessel-related myocardial infarction, or ischaemia-driven target lesion revascularisation—at 12 months. Kandzari and colleagues also planned, using pooled data from BIOFLOW II, BIOFLOW IV, and BIOFLOW V, to perform a Bayesian analysis of the primary endpoint. “To ensure consistency and validity of pooled events, all BIOFLOW II and BIOFLOW IV events were re-adjudicated, including additional events not previously adjudicated for those studies,” he said.
Procedural success was significantly higher, in the primary analysis, with Orsiro: 93.9% vs. 90.1% for Xience (p=0.019). This finding, Kandzari reported, was driven by a higher rate of in-hospital myocardial infarction in the Xience arm (6.7% vs. 3.9% for Orsiro; p=0.029). Furthermore, at 12 months, the rate of target lesion failure was significantly lower with Orsiro—6.2% vs. 9.6% for Xience; p=0.04. In terms of the individual components of the primary endpoint, there were no significant differences in the rate of cardiac death or of target lesion revascularisation between groups but target vessel-related myocardial infarction was significantly lower with Orsiro (4.7% vs. 8.3%, respectively; p=0.016). These results were independent of baseline and procedural characteristics.
According to the pooled Bayesian analysis—including 1,466 patients who received Orsiro and 742 who received Xience—the mean 12-month rate of target lesion failure was 6.3±0.8 for the biodegradable polymer and 8.9±1.2 for Xience (a difference of -2.6). Kandzari stated that posterior probability, with Osiro compared with Xience, was 100% for non-inferiority and was 96.9% (in a post-hoc analysis) for superiority.
Speaking to Cardiovascular News, Kandzari said: “The difference in target lesion failure in BIOFLOW V was largely—but not exclusively—driven by significant differences in periprocedural related myocardial infarction, a difference that persisted even for larger myocardial infarction events. However, even beyond 30 days, there was a trend toward higher target vessel-related myocardial infarction in the Xience group. Further, rates of target lesion revascularisation and cardiac death were also numerically but not statistically significantly lower in the Orsiro group. Therefore, lower event rates in all three categories ultimately contributed to the observed lower target lesion failure rate.”
He speculated that the lower myocardial infraction rate “may at least in part” be a result of ultra-thin struts of Orsiro. “In review of comparative stent data relative to strut thickness, both early and late myocardial infarction events are lower with thinner strut stents,” Kandzari commented.
Concluding his ESC presentation, Kandzari said: “These results endorse the safety and efficacy of the ultra-thin Orsiro biodegradable polymer sirolimus-eluting stent in patients who are representative of those treated with in clinical practice and advance a new standard for drug-eluting stent comparison”.
To coincide with its presentation at the ESC congress, BIOFLOW V was simultaneously published in The Lancet.