Pathological finding of sirolimus-eluting stent (SES) restenosis lesion with black hole appearance on intravascular ultrasound.

Restenosis still occurs, even with the sirolimus-eluting stent (SES), and the precise mechanisms have not yet been elucidated. In the present case, focal in-stent stenosis was discovered on angiography 16 months after SES implantation. Intravascular ultrasound revealed an echolucent homogeneous zone, which has been termed "black hole". A sample of stenotic tissue retrieved by aspiration revealed neointimal hyperplasia, composed of proteoglycans and smooth muscle cells with scanty cellularity. Furthermore, infiltration of many macrophages and T lymphocytes coexisted in the restenotic tissue. These findings suggest that delayed healing is 1 of the mechanisms of SES restenosis.