SCAAR: Stent Thrombosis Rates in DES vs. BMS

The new generation of drug eluting coronary stents are associated with lower late and very late stent thrombosis rates after implantation, compared to its preceding models, according to results from the SCAAR trial, presented Aug. 30 as part of ESC Congress 2014.

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Despite being safe and effective, old-generation drug eluting coronary stents (o-DES) have been associated with an increased propensity of late stent thrombosis. New generation drug eluting coronary stents (n-DES) however, have been developed with new alloys, delivery systems, improved and bioresorbable polymers, and new anti-proliferative agents.

In light of these advancements the trial investigation, led by Christoph Varenhorst, MD, PhD, Uppsala Clinical Research Center, Suppsala, Sweden, evaluated all implantations with bare metal stents (BMS), o-DES (Cordis Cypher, Boston Scientific Taxus Liberté, and Medtronic Endeavor) and n-DES in the Swedish Coronary Angiography and Angioplasty Registry between Jan. 1, 2007 and Jan. 8 2014. Results showed that the overall risk of stent thrombosis was lower in both n-DES and o-DES compared with BMS up to one year (n-DES vs BMS: adjusted risk ratio (RR) 0.50 (0.41-0.59) and o-DES vs BMS: 0.55 (0.46-0.67), both p<0.001). One year after stent implantation and onward, the risk for stent thrombosis was higher in o-DES compared with BMS (adjusted RR, 1.81 (1.44-2.28), p<0.001). N-DES were linked with similar low stent thrombosis rates as BMS progressing one year and beyond (adjusted RR 1.17 (0.88-1.56), p=0.279).

The investigators note that the non-randomized comparison between the stent types was adjusted for all available confounders "but there is always a possibility of bias because of unknown confounders," they note. "Nonetheless, the reliability of our results are strengthened by a complete angiographic long-term follow up, registry source-data verification and the use of definite, angiographically proven stent thrombosis as only endpoint measure," they conclude.

Keywords: Reproducibility of Results, Odds Ratio, Registries, Follow-Up Studies, Coronary Angiography, Drug-Eluting Stents, Polymers, Coronary Thrombosis, Angioplasty

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