Novel biodegradable sirolimus-eluting stents non-inferior to durable everolimus-eluting stents [BIOSCIENCE trial]

1. In the BIOSCIENCE trial, a novel biodegradable polymer sirolimus-eluting stent (Orsiro) was non-inferior to the durable polymer everolimus-eluting stent with respect to cardiac death, target-vessel myocardial infarction (MI), and clinically-indicated target lesion revascularization.

2. Orsiro stents were associated with improved outcomes compared to durable polymer everolimus-eluting stents in the STEMI subgroup.

Evidence Rating Level: 1 (Excellent)

Study Rundown: As drug-eluting stents are part of the current standard of care in patients undergoing percutaneous coronary intervention (PCI), stent design refinements are a primary emphasis in research and study efforts in order to further reduce adverse events. Results of a large multi-center randomized single-blind study (the BIOSCIENCE trial) published in Lancet today showed that a novel biodegradable polymer sirolimus-eluting stent (Orsiro) was non-inferior to the durable polymer everolimus-eluting stent with respect to such major clinical outcomes as cardiac death, target-vessel MI, and clinically-indicated target lesion revascularization at 12 months. The study was well-designed and adequately powered, with more than 2,000 participants. One caveat is that the chosen margin of non-inferiority (3.5%) was more than 50% of the observed primary endpoint, which may adversely affect the robustness of results.

The study was funded by the Clinical Trials Unit, University of Bern, and Biotronik, Bülach, Switzerland.

Click to read the study, published today in The Lancet

Relevant Reading: Biodegradable-polymer drug-eluting stents vs. bare metal stents vs. durable-polymer drug-eluting stents: a systematic review and Bayesian approach network meta-analysis

In-Depth [randomized controlled trial]: This is a large multi-center, randomized-controlled, single-blind non-inferiority trial that compared a novel ultrathin strut biodegradable polymer sirolimus-eluting stent (Orsiro) to durable polymer everolimus-eluting stent. Orsiro consists of an ultrathin (60 um) cobalt-chromium L605 platform covered with an amorphous silicon-carbide layer, and releases sirolimus from a biodegradable poly-L lactate polymer. The primary endpoint was target lesion failure, which was a composite of cardiac death, target vessel MI, and clinically indicated target lesion revascularization within 12 months. The final analyses included 1063 patients assigned to Orsiro and 1056 patients assigned to durable polymer everolimus-eluting stents.

By 12 months, primary endpoint of target lesion failure had occurred in similar proportions in patients receiving Orsiro stents compared to patients receiving durable polymer everolimus-eluting stents, establishing non-inferiority for Orsiro (absolute risk difference, -0.14%; upper limit of the one-sided 95% confidence interval [CI], 1.97%; p=0.0004 in one-sided non-inferiority analysis). The individual components of the primary endpoint – including cardiac death, target vessel MI, and clinically indicated target lesion revascularization – were all similar in both stent groups.

Results were robust – in a hypothetical worst-case scenario where all patients lost to follow-up or who withdrew consent before 12 months in the experimental group had died, non-inferiority would still be maintained for Orsiro stents (risk difference, 0.013%; 95% CI, -0.008 to 0.033; p=0.036 for non-inferiority).

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