Ultrathin Strut Biodegradable Polymer Sirolimus-Eluting Stent Versus Durable Polymer Everolimus-Eluting Stent for Percutaneous Coronary Revascularisation (BIOSCIENCE): A Randomised, Single-Blind, Non-Inferiority Trial

Study Questions:

What is the safety and efficacy of a novel, ultrathin strut cobalt-chromium stent releasing sirolimus from a biodegradable polymer, as compared with a thin strut durable polymer everolimus-eluting stent (EES)?


The investigators conducted a randomized, single-blind, non-inferiority trial with minimum exclusion criteria at nine hospitals in Switzerland. They randomly assigned (1:1) patients ages ≥18 years with chronic stable coronary artery disease or acute coronary syndromes undergoing percutaneous coronary intervention to treatment with biodegradable polymer sirolimus-eluting stents (SES) or durable polymer EES. Randomization was via a central web-based system and stratified by center and presence of ST-segment elevation myocardial infarction (STEMI). Patients and outcome assessors were masked to treatment allocation, but treating physicians were not. The primary endpoint, target lesion failure (TLF), was a composite of cardiac death, target vessel MI, and clinically indicated target lesion revascularization at 12 months. A margin of 3.5% was defined for non-inferiority of the biodegradable polymer SES compared with the durable polymer EES. Analysis was by intention to treat. The trial is registered with ClinicalTrials.gov, number NCT01443104.


Between February 24, 2012, and May 22, 2013, the investigators randomly assigned 2,119 patients with 3,139 lesions to treatment with SES (1,063 patients, 1,594 lesions) or EES (1,056 patients, 1,545 lesions). A total of 407 (19%) patients presented with STEMI. TLF with biodegradable polymer SES (69 cases; 6.5%) was non-inferior to durable polymer EES (70 cases; 6.6%) at 12 months (absolute risk difference, −0.14%; upper limit of one-sided 95% confidence interval [CI], 1.97%; p for non-inferiority < 0.0004). No significant differences were noted in rates of definite stent thrombosis (9 [0.9%] vs. 4 [0.4%], rate ratio [RR], 2.26; 95% CI, 0.70–7.33; p = 0.16). In prespecified stratified analyses of the primary endpoint, biodegradable polymer SES were associated with improved outcome compared with durable polymer EES in the subgroup of patients with STEMI (7 [3.3%] vs. 17 [8.7%]; RR, 0.38; 95% CI, 0.16–0.91; p = 0.024, p for interaction = 0.014).


The authors concluded that biodegradable polymer SES were non-inferior to durable polymer EES for the combined safety and efficacy outcome TLF at 12 months.


In this multicenter, single-blind, randomized trial, an ultrathin strut biodegradable polymer SES was non-inferior to a durable polymer EES for TLF at 12 months in a patient population with minimum exclusion criteria and high adherence to dual antiplatelet therapy. No significant differences were documented between the two treatment groups in the individual components of the primary endpoint, or in any of the secondary clinical endpoints. Furthermore, treatment with biodegradable polymer SES was associated with a reduced risk of the primary endpoint, TLF, compared with durable polymer EES in STEMI patients, and needs additional prospective evaluation.

Clinical Topics: Acute Coronary Syndromes, Invasive Cardiovascular Angiography and Intervention, Stable Ischemic Heart Disease, Interventions and ACS, Chronic Angina

Keywords: Myocardial Infarction, Acute Coronary Syndrome, Coronary Restenosis, Thrombosis, Polymers, Intention to Treat Analysis, Confidence Intervals, Sirolimus, Angioplasty, Balloon, Coronary, Stents, ESC Congress

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