Randomized comparison of sirolimus eluting, and biolimus eluting bioresorbable polymer stents: the SORT-OUT VII optical coherence tomography study.

Aims: To show non-inferiority of the 67- or 87 µm thick, sirolimus-eluting Orsiro drug eluting stent (DES) to the 122 µm thick, biolimus-eluting Nobori DES regarding size of vessel lumen outside the stent at 13-month follow-up.
Methods and Results: This study was a substudy to the SORT-OUT VII trial, a prospective, 1:1-randomized, comparison of the two stents in patients with stable coronary artery disease or acute coronary syndrome. Optical coherence tomography was acquired after percutaneous coronary intervention and at 13-month follow-up. The substudy was powered to access non-inferiority (Δ = 0.60 mm2) of the Orsiro DES to the Nobori DES for the primary endpoint of mean extra stent lumen (ESL) i.e. vessel lumen outside the stent at 13-month follow-up. We randomized 124 patients to Orsiro (n = 60) or Nobori (n = 64). Due to a difference in the one-sided 95%-confidence interval of 0.26 mm2, but increased to 0.82 mm2 after appropriate log-transformation, it could not be rejected that Orsiro exceeded the non-inferiority limit. Testing for superiority, Orsiro had a significantly larger mean ESL at follow-up (Orsiro: 0.11 mm2 [0.02;0.30] mm2, Nobori: 0.03 mm2 [0.00;0.17] mm2, P = 0.04). Stent strut coverage was, Orsiro: 97.6 % [93.8;99.4]%, and Nobori: 96.3 % [90.5;98,6]% (P = 0.13).
Conclusion: Orsiro DES had a significantly larger mean ESL at follow-up and it could not be excluded that Orsiro exceeded the limit for non-inferiority. Nobori DES had a more heterogeneous distribution of neointima but stent strut coverage did not differ significantly between the two stents.
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