Aims: Since the intravascular ultrasound (IVUS) cannot detect neointimal layers in the majority of sirolimus-eluting stents (SES) at the chronic phase, it is still controversial to what extent SES remain uncovered. However, optical coherence tomography (OCT) with excellent resolution may be able to detect thinner neointima.
Methods and results: A total of 34 patients (57 SES) underwent OCT and IVUS evaluations at 6-month follow-up. The thickness of neointima on each SES strut cross-section and strut apposition to the vessel wall was evaluated. By OCT evaluation, the median (25th, 75th percentiles) neointima thickness was 52.5 microm (28.0 microm, 147.6 microm) and the prevalence of struts covered by thin neointima undetectable by IVUS was 64%. The average rate of neointima-covered struts in an individual SES was 89%. Nine SES (16%) showed full coverage by neointima, whereas the remaining stents had partially uncovered strut lesions. Among the 6840 struts visualized by OCT in all of the SES, 79 struts showed malapposition without neointimal coverage, and were frequently observed in the areas of SES overlap.
Conclusion: At 6 months, most of the SES were covered with thin neointima, but few showed full coverage.