Fibrin Clot Visualized by Optical Coherence Tomography
Optical coherence tomography (OCT) is a recently developed optical imaging technique that provides high-resolution (≈10 to 20 μm) cross-sectional images of vessels.1 It has been reported that OCT images of white and red thrombus were characterized as backscattering protrusions in the coronary lumen.2 However, OCT characteristics of fibrin clot composed of fibrin material and few blood cells have not been described.
The coronary arteries of a 75-year-old man who died from acute myocardial infarction were obtained at autopsy. Histopathological examination showed fibrin clot composed of fibrin material and few blood cells in the coronary artery (Figure, A and B). Before proceeding with a standard histopathological examination, we visualized the coronary artery using OCT. OCT characteristics of fibrin clot, a signal-rich structure without backscattering, were obviously different from white or red thrombus that were characterized as a signal-rich structure with backscattering (Figure, C).
Although drug-eluting stents have reduced rates of restenosis and late lumen loss compared with bare-metal stents, thrombosis has emerged as a major concern. In addition, delayed arterial healing, as evidenced by persistence of fibrin clot after DES implantation, has been demonstrated. Although OCT might be useful for monitoring structural changes after DES implantation, it might be difficult, using OCT, to discriminate fibrin clot from minimal neointimal formation after DES implantation.