Tissue coverage of paclitaxel and sirolimus eluting stents in long term follow-up: Optical coherence tomography study

Background: Implantation of drug eluting stents (DES) has become a standard treatment ofpatients undergoing percutaneous coronary intervention (PCI). Incomplete strut coverage isa potential risk factor for late stent thrombosis. Optical coherence tomography (OCT) enablesin vivo identification of incomplete neointimal coverage.Methods: Study included 62 patients after sirolimus eluting stents (SES) or paclitaxel elutingstents (PES) implantation. OCT examination was performed at least 24 months after theinitial procedure (35.4± 9.4 months). In cross-sectional still frames selected from each 1 mm ofanalyzed stents a total number of visible struts and number of struts with or without completeneointimal coverage was assessed. Measurements of neointimal coverage, presented as a meanthickness of tissue, were performed. Patients were followed up for 3 years and the frequency ofmajor adverse cardiac events was recorded.Results: In the analyzed 28 SES and 37 PES 9998 struts were identified. Complete neointimalcoverage was observed in 83.5% and 79.2% of SES and PES struts respectively (p = 0.48).There was no difference in incidence of not covered or malapposed struts between SES and PES groups. Mean thickness of the tissue covering SES struts was 0.165 ± 0.095 mm, and 0.157 ± 0.121 mm for PES. The mean neointimal thickness difference (SES vs. PES) was notstatistically significant. In a 36 months follow-up 1 death was observed — potentially attributedto stent thrombosis.Conclusions: A long term OCT follow-up after DES implantation shows high incidence ofuncovered struts regardless of the stent type. Clinical significance of this finding remains questionableand requires further large scale trials