Results of the BIOSCIENCE study that were presented at the ESC Annual Congress by Dr. Thomas Pilgrim, University Clinic for Cardiology, Bern, Switzerland, show that the 5-year risk of target lesion failure among patients undergoing percutaneous coronary intervention (PCI) is similar after implantation of the ultrathin-strut, biodegradable-polymer sirolimus-eluting stents as compared with thin-strut, durable-polymer, everolimus-eluting stents. However, higher incidence of all-cause and non-cardiovascular mortality in patients treated with the biodegradable polymer sirolimus-eluting-stents as compared with the durable-polymer stents eluting everolimus warrant careful scrutiny in ongoing clinical trials. The announcement of the results of this trial at the ESC was accompanied by a publication in the Lancet.
This independent, investigator-initiated, multi-center, randomized, controlled non-inferiority study was conducted in order to compare the 5-year outcomes of safety and efficacy of the sirolimus-eluting stent with a biodegradable polymer (Orsiro) versus an everolimus-eluting stent with a durable polymer (Xience Prime). In a population of 2119 patients with chronic stable coronary artery disease or acute coronary syndromes recruited between February 2012 and May 2013, BIOSCIENCE aimed to compare these products with a primary endpoint of Target Lesion Failure (TLF), defined as a composite of cardiac death, target vessel Q-wave or non-Q-wave myocardial infarction (MI) and clinically driven Target Lesion Revascularization (TLR) at 1 year. Intention to treat was the primary analysis performed. In the trial, the time to the first event for each outcome, numbers of patients and Kaplan-Meier estimates of cumulative incidence were reported.
“I think the Orsiro stent has the potential to be as established as other newer generation drug-eluting stents. We will see if there is a difference in large meta-analyses of randomized controlled trials, but as for now, I think it will be as good as the newer generation drug-eluting stents.”- Dr. Thomas Pilgrim, M.D.
Pilgrim and his colleagues reported that 95% of all patients were able to complete 5 years of follow-up. Target lesion failure occurred in 20.2% and 18.8 % of those treated with biodegradable-polymer sirolimus-eluting stents and durable-polymer everolimus-eluting stents respectively. (RR 1.07; 95% CI, 0.88–1.31; p = 0.487). However, all-cause mortality was significantly higher in patients treated with biodegradable-polymer sirolimus-eluting stents than in those treated with durable-polymer everolimus-eluting stents (14.1% vs. 10.3%; RR, 1.36; 95% CI, 1.06–1.75; p = 0.017), driven by a difference in noncardiovascular deaths (mainly due to cancer). The investigators reported no difference between groups in the cumulative incidence of definite stent thrombosis at 5 years (1.6% in both groups; 1.02, 0.51–2.05; p = 0.950).
The results were encouraging as the primary endpoint results from the 12-month follow-up demonstrated that Orsiro met its study objective of non-inferiority versus Xience Prime and the 5-year risk of target lesion failure did not differ between patients undergoing percutaneous coronary intervention after implantation of ultrathin-strut, biodegradable-polymer, sirolimus-eluting stents or thin-strut, durable-polymer, everolimus-eluting stents. While the higher risk of all-cause mortality in Orsiro warrants careful observation in patients, its safety and efficacy in relation to ST-segment elevation myocardial infarction (STEMI) is currently under evaluation in the BIOSTEMI trial. Expressing his optimism regarding the future of Orsiro, Dr. Thomas Pilgrim remarks, “I think the Orsiro stent has the potential to be as established as other newer generation drug-eluting stents. We will see if there is a difference in large meta-analyses of randomized controlled trials, but as for now, I think it will be as good as the newer generation drug-eluting stents.”
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