BIOFLOW V demonstrates potential of ultrathin bioresorbable sirolimus-eluting stent in PCI
The use of an ultrathin, bioresorbable polymer sirolimus-eluting stent resulted in better outcomes compared with a durable polymer everolimus-eluting stent in patients undergoing percutaneous coronary intervention (PCI) for de-novo, native coronary lesions, according to findings from the BIOFLOW V trial.
“[T]hese findings … show significant differences in target lesion failure and target vessel-related myocardial infarction [MI] that favour ultrathin strut, bioresorbable polymer sirolimus-eluting stents over durable polymer everolimus-eluting stents,” said the researchers.
At 12 months, incidence of target lesion failure (a composite of cardiovascular death, target vessel-related MI, or ischaemia-driven target lesion revascularization) was lower among patients who received a bioresorbable polymer sirolimus-eluting stent compared with those who received a durable polymer everolimus-eluting stent (6 percent vs 10 percent; p=0.0399), which was mostly due to a lower incidence of target vessel-related MI among patients who received the bioresorbable stent (5 percent vs 8 percent; p=0.0155). [Lancet 2017;doi:10.1016/S0140-6736(17)32249-3]
The incidence of cardiac death between the patients receiving the bioresorbable and durable stents was comparable at 12 months (<1 percent vs 1 percent; p=0.1153), as was the incidence of clinically driven target lesion revascularization (2 percent in each group; p=0.6856), while incidence of in-hospital MI was higher among patients using a durable stent compared with a bioresorbable one (7 percent vs 4 percent; p=0.0295).
A pooled analysis of primary endpoint results from this trial as well as that from the BIOFLOW II and IV trials (n=2,208) showed a 100 percent Bayesian posterior probability of the noninferiority of the bioresorbable polymer sirolimus-eluting stent to the durable polymer everolimus-eluting stent (Bayesian estimate target lesion failure rate difference, -2.6 percent).
In this multicentre trial (90 hospitals in 13 countries), adults (n=1,334) with ischaemic heart disease undergoing elective or urgent PCI were randomized to receive an ultrathin strut (60 µm) bioresorbable polymer sirolimus-eluting stent (n=884, mean age 64.5 years, 25 percent female) or a durable polymer everolimus-eluting stent (81 µm, n=450, mean age 64.6 years, 27 percent female). Approximately 50 percent of patients had acute coronary syndrome, while about one-third had diabetes mellitus at baseline.
All patients received aspirin (≥150 mg in 24 hours) and either clopidogrel (75 mg/day), ticagrelor (90 mg BID), or prasugrel (10 mg/day or 5 mg/day for individuals <60 kg) prior to the procedure, and dual antiplatelet therapy for ≥6 months post-procedure.
“[I]t is possible that the thinner stent struts of the bioresorbable polymer sirolimus-eluting stent … contributed to the lower frequencies of procedure-related MI and stent thrombosis observed,” said the researchers. “This observation is particularly relevant because the difference in adverse events is observed during a period before complete polymer dissolution.”
“[I]f the benefit is found to be related to an ultrathin stent design, a new focus in iterative stent development could be to further minimize strut thickness while maintaining drug delivery and mechanical properties,” they said.
As there is no evidence to suggest a class effect, the researchers attest that each specific stent type should be tested in clinical trials to determine the comparable safety and efficacy of bioresorbable polymer vs durable polymer drug-eluting stents. They also cautioned that the results may not extend to the entire population due to trial design excluding certain high-risk groups.