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

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.

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.

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.

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.