Background: Implantation of drug eluting stents (DES) has become a standard treatment of patients undergoing percutaneous coronary intervention (PCI). Incomplete strut coverage is a potential risk factor for late stent thrombosis. Optical coherence tomography (OCT) enables in vivo identification of incomplete neointimal coverage.
Methods: Study included 62 patients after sirolimus eluting stents (SES) or paclitaxel eluting stents (PES) implantation. OCT examination was performed at least 24 months after the initial procedure (35.4± 9.4 months). In cross-sectional still frames selected from each 1 mm of analyzed stents a total number of visible struts and number of struts with or without complete neointimal coverage was assessed. Measurements of neointimal coverage, presented as a mean thickness 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 attributed to 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 questionable and requires further large scale trials.