Polymer-Free vs. Biodegradable Polymer Stents: SORT OUT IX 5-Year Outcomes

In a constant strive to achieve life time management, interventional cardiologists focus on optimizing coronary scaffolds, which calls for the development of devices with better long-term performance and safety profiles, eliminating durable polymers and optimizing antiproliferation drug release. 

To this end, Jensen et al. have published the SORT OUT IX 5-year followup outcomes. This multicenter, randomized, non-inferiority study compared the long term performance of the biolimus A9-coated polymer-free stent BioFreedom vs. the ultrathin-strut biodegradable-polymer sirolimus-eluting stent  Orsiro. 

The study included 3,151 patients, with very low loss rate at followup (0.3%), assessed at years 1 and 5 (according to registry). The primary end point was target vessel failure (TLF), a combination of cardiac death, target vessel MI (TV-MI) or target lesion revascularization (TLR).

During the first 12 months, TLF rate was 5.0% for BioFreedom vs. 3.7% for Orsiro (RR 1.34; CI95%: 0.96–1.89; p=0.089). While this difference did not reach statistical significance, the TLR component was: 3.5% for BioFreedom vs. 1.3% for Orsiro (RR 2.76; CI95%: 1.65–4.62; p<0.001). This finding suggests lower initial clinical efficacy for BioFreedom in maintaining the treated coronary lumen. 

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Safety events such as all-cause mortality (2.0% vs 2.7%), cardiac death (1.0% vs 1.8%), and definite stent thrombosis (0.7% in both groups) were low and similar, with no significant differences.

At extended followup (1 to 5 years),  TLF incidence was 9.6% for BioFreedom and 8.8% for Orsiro (RR 1.11; 95% CI: 0.88–1.41; p=0.388), with comparable TLR rates (4.4% vs 3.9%; RR 1.13; 95% CI: 0.80–1.62; p=0.484). Other events such as lesion related infarction (3.8% vs 3.5%), cardiac death (4.2% vs 3.6%) and definite thrombosis (0.8% vs 1.1%) also showed no statistically significant differences, which suggests similar clinical results after the second year. 

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By the end of year 5, accumulated TLF rate resulted 14.1% for BioFreedom and 12.0% for Orsiro (RR 1.19; 95% CI: 0.97–1.44; p=0.088), again with no statistical significance.

Conclusions

The SORT OUT IX 5-year outcomes have shown long term comparable safety in terms of death, MI or stent thrombosis. However, the polymer free strategy showed better TLR rate during the first year, which could be attributed to its rapid drug release (28 days) and thicker struts (120 µm) vs Orsiro (60–80 µm and 3-month release). 

Original Title: Five-year outcomes of a drug-coated polymer-free biolimus-eluting stent versus an ultrathin-strut biodegradable-polymer sirolimuseluting stent.

Reference: Jensen LO, Jakobsen L, Eftekhari A, Ellert-Gregersen J, Støttrup NB, Engstrøm T, Kahlert J, Freeman P, Veien KT, Jensen RV, Lassen JF, Junker A, Christiansen EH. Five-year outcomes of a drug-coated polymer-free biolimus-eluting stent versus an ultrathin-strut biodegradable-polymer sirolimus-eluting stent. EuroIntervention. 2025 Jun 2;21(11):e617-e628. doi: 10.4244/EIJ-D-24-00586. PMID: 40464671; PMCID: PMC12105667.