Histology of highly echolucent regions in optical coherence tomography images from two patients with sirolimus-eluting stent restenosis.

We report on two patients with sirolimus-eluting stent (SES) restenosis lesions who showed highly echolucent regions by optical coherence tomography (OCT) and who could be assessed histologically after removal by directional coronary atherectomy (DCA). One restenosis lesion had a bilayer structure of hyperechoic outer layers and highly echolucent inner layers on OCT images and histologically exhibited myxomatous neointima tissue in the highly echolucent regions; another restenosis case showed patchy and highly echolucent regions throughout the layers and its histology revealed fibrin thrombosis. We should be aware that patterns of echolucent on OCT images may have various histology. OCT allows the visualization of fine lesions that conventional intravascular ultrasound (IVUS) cannot provide. The OCT images of drug-eluting stent restenosis lesions often show echolucent regions [Shuzoh et al., EuroInterv 2006;1:484]. However, no histological study of the lesions has been reported to date. Here we report on two patients with SES restenosis lesions that showed highly echolucent regions by OCT and that could be assessed histologically after removal by DCA.