Clinical and pathological characteristics of homogeneous and nonhomogeneous tissue of in-stent restenosis visualized by optical coherence tomography

Adiponectin as a potential therapeutic target for the treatment of restenosis

Restenosis is a pathologic re-narrowing of a coronary artery lesion after mechanical injury. Its pathophysiological mechanisms have not been fully elucidated at present, but are thought to include inflammation, vascular smooth muscle cell (VSMC) proliferation, and matrix remodeling, beginning with insufficient endothelium healing. Restenosis presents with angina symptoms or acute coronary syndromes and lead to a revascularization, either with coronary artery bypass or repeat percutaneous coronary intervention. Some studies have reported that hypoadiponectinemia has been an independent risk factor for the onset of acute coronary syndromes and restenosis. Accumulating evidence shows that low concentrations of adiponectin may be involved in impairing endothelium functions, inflammation, and VSMC proliferation that lead to restenosis. Preclinical studies have proven that adiponectin promotes endothelium healing, effectively inhibits inflammation, and maintains contractile phenotypes of VSMCs, indicating that it may be developed as a new therapeutic target for the treatment of restenosis.

Formation and Transformation of Neointima after Drug-eluting Stent Implantation: Insights from Optical Coherence Tomographic Studies

After coronary stent implantation, neointima formation resembles the wound healing process as it involves the sequential processes of inflammation, granulation, and remodeling. Because antiproliferative drugs and polymers of drug-eluting stents (DESs) delay vascular healing compared with bare metal stents, fibrin deposition can remain long after stent implantation, or inflammation can be excessive. Delayed vascular healing can be associated with adverse clinical outcomes including DES thrombosis or restenosis, and poor endothelization of DES neointima can accelerate neoatherosclerotic change inside the neointima, further contributing to luminal restenosis or neointimal instability. Despite the lack of correlation between pathologic and optical coherence tomography (OCT) findings, OCT assessments of neointima under various circumstances can reveal vascular responses to stent therapy. Homogeneous, heterogeneous, and layered neointima patterns can be recognized by OCT and can change with time. Homogeneous neointima might be associated with better clinical outcomes after DES implantation, whereas non-homogeneous neointima or neoatherosclerotic change can be associated with poorer clinical outcomes. However, limited data are currently available, and further studies are required to comprehensively address these questions.

Coronary angioscopic imaging of in-stent restenosis after biolimus-eluting coronary stent implantation

A 69-year-old man underwent repeat percutaneous coronary intervention for in-stent restenosis in the obtuse marginal artery 8 months after biolimus-eluting stent (2.5 × 28 mm Nobori stent, Terumo, Tokyo, Japan) implantation. Coronary angiography showed focal stenosis in the distal part of the stent. Intravascular ultrasound revealed low echoic heterogeneous intimal tissue. Optical coherence tomography also revealed a heterogeneous finding classified as a layered pattern. Coronary angioscopy detected a white mass with a paste-like appearance at the stenosis extending around the in-stent restenosis as a thin membrane where stent strut could be seen transparently. A small part of the mass was swinging in the blood stream. Coronary angioscopic imaging was beneficial for the understanding of the suspected mechanism and feature of the in-stent restenosis after second-generation stent implantation, which was apparently different from neointimal hyperplasia after bare-metal stent implantation. <Learning objective: The learning objectives of this case report include understanding the mechanism of in-stent restenosis after second-generation drug-eluting stent implantation by showing the coronary angioscopic imaging beyond the other intravascular imaging. In particular, this case can make the general and interventional cardiologists learn that the mechanism of in-stent restenosis <1 year is different from that after bare-metal stent implantation.>.