Date: 03 Mar 2013

Very long-term follow-up of strut apposition and tissue coverage with Biolimus A9 stents analyzed by optical coherence tomography

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First generation drug-eluting stents (DES) are associated with reduced in-stent restenosis but significant increased risk of very late stent thrombosis (VLST). The absence of polymer in DES systems may reduce the occurrence of VLST. Optic coherence tomography (OCT) has been used for stent analysis as a surrogate safety endpoint. This study aimed to assess the long-term follow up of strut apposition and tissue coverage of BioMatrix™ DES by OCT. 20 patients undergoing BioMatrix™ DES (n = 15) or S-Stent™ BMS (n = 5) implantation were followed for at least 5 years and evaluated by quantitative coronary angiography, intravascular ultrasound, and OCT. The difference between the stent types was evaluated by nonparametric Mann–Whitney U test while categorical variables were evaluated by Fisher exact test. Rates of in-stent late loss were similar between groups [0.40 (0.21;0.77) vs. 0.68 (0.66; 0.82) mm, p = 0.205, for BioMatrix™ and S-Stent™, respectively]. The vessel, stent and lumen volumes did not differ between groups. Patients treated with BioMatrix™ had significantly less stent obstruction [5.6 (4.4;9.7) vs. 28.6 (24.7;29.0) %, p = 0.001]. OCT analysis of 12 stents (Biomatrix™ = 9 and S-Stent™ = 3) demonstrated 126 (8.7 %) uncovered struts in the BioMatrix™ group compared to 23 (4.0 %) in the S-Stent™ group (p = 0.297), being the majority of them well apposed (117/126 and 21/23, respectively, p = 0.292). Only 9 (0.6 %) struts in the DES and 2 (0.4 %) struts in the BMS groups were simultaneously uncovered and malapposed (p = 0.924). BioMatrix™ DES was associated with lower rates of in-stent obstruction, and similar percentage of neointimal coverage on struts and of complete strut apposition.