Non-obstructive aortic angioscopy is an intravascular imaging modality applied to safely acquire real visible light-based detailed images of the inner surface of the aortic lumen in vivo on a real-time basis, which are not well detected by other imaging modalities including computed tomography (CT), magnetic resonance imaging (MRI), or ultrasound imaging. Application of this technique and usage in research and in clinical practice can be facilitated by the development of uniform standards of its methodology, interpretation, diagnosis, reporting, and terminology. The aim of this document is to make the output of the Working Group of Japan Vascular Imaging Research Organization for Standardization of Non-obstructive Aortic Angioscopy for the purpose of announcing the consensus standards for acquisition, measurement, and reporting of non-obstructive aortic angioscopy studies as version 2017.

Percutaneous endoscopy for direct visualization of the cardiac interior, i.e., percutaneous cardioscopy, was developed in Japan in 1980. Approved by Japanese Ministry of Health, Welfare and Labor, this imaging technique has been used for diagnosis and evaluation of interventional and surgical treatment of various categories of heart diseases. This article reviews recent advances in percutaneous cardioscopy.

Percutaneous cardioscopy has demonstrated that the endocardial surface exhibits various colors characteristic of different heart diseases. This imaging modality can now be used for evaluation of the severity of myocardial ischemia and staging of myocarditis. Myocardial blood flow (MBF) recovery induced by vasodilating agents or percutaneous coronary interventions can be clearly visualized. Subendocardial microvessels can be seen through the endocardium. Combined use of cardioscopy and intracardiac ultrasonography (ICUS) is useful for evaluation of morphological and functional changes in the cardiac chambers and valves. Cardioscope-guided endomyocardial biopsy enables pin-point biopsy of diseased myocardium. Dye-image and fluorescent cardioscopy were developed for evaluation of the subendocardial MBF or tissue fluid flow. These imaging techniques have demonstrated that myocardial microcirculation disturbance remains frequently after angiographic successful percutaneous coronary interventions (PCI). Cardioscopy is also useful for evaluation of percutaneous transseptal mitral commissurotomy or open-heart surgery of various categories of heart disease. In near future, cardioscope would be used for guidance of myocardial ablation, valvuloplasty, or transendocardial angiogenic or myogenic therapy.

In conclusion, percutaneous cardioscopy has the potential to contribute to our understanding of heart disease and to assist intracardiac therapies.

Diabetes is characterized by hyperglycemia and certainly indicates various micro- and macro-vascular complications. Macro-vascular complications include ischemic coronary artery disease due to atherosclerosis, which is a leading cause of mortality in diabetic patients. Diabetic retinopathy (DR) is considered as a specific marker of micro-vascular complications and is included in the criteria for diagnosis of diabetes. The ultimate goal of diabetes treatment is to inhibit the progression of systemic atherosclerosis and prevent fatal cardiovascular events like acute coronary syndrome (ACS). Although diabetes involves both micro- and macro-vascular diseases, the relationship between DR and severity of coronary atherosclerosis, fundamental to ACS, is unclear. Moreover, the correlation of the degree of glucose metabolism disorder with coronary atherosclerosis remains unclear. The American Diabetes Association considers prediabetes as a high risk for diabetes and cardiovascular events in the future. However, coronary atherosclerosis in prediabetic patients has not been fully investigated.

Coronary angioscopy (CAS) is a useful intravascular imaging modality for assessing the characteristics of atherosclerotic plaques and its severity in vivo. Recently, CAS has shown the above relationships. Herein, we review the angioscopic findings and subsequent therapeutic implications in patients with glucose metabolism disorders.

Background: Angioscopy was performed in a group of patients in the PRASugrel For Japanese PatIenTs with Coronary Artery Disease Undergoing Elective PCI (PRASFIT-Elective) study to determine the incidence and clinical features of stent thrombosis. Stent thrombosis is an infrequent, but potentially severe event that may require revascularization or lead to other clinically significant events. Its incidence and clinical features in Japanese patients undergoing elective percutaneous coronary intervention (PCI) are poorly understood, especially in those receiving dual antiplatelet therapy with prasugrel or clopidogrel in combination with aspirin.

Methods: Coronary angioscopy was performed before and at 36 weeks after elective PCI in 19 and 14 patients treated with prasugrel and clopidogrel, respectively, across eight participating institutions. Coronary angioscopic images were adjudicated by independent staff at a central laboratory to assess intrastent thrombus, neointimal coverage, and plaque color.

Results: The proportion of stents with a red thrombus decreased from 57.9% (11/19) to 21.1% (4/19) in the prasugrel group (P = 0.0082) and from 50.0% (7/14) to 35.7% (5/14) in the clopidogrel group (P = 0.3173) at stenting to the follow-up visit. Platelet reactivity at 4 weeks was similar between patients with or without a red intrastent thrombus. Stent coverage was classified as Grade 1 in most of the patients, and the yellow plaque classification was Grade 0–2 in most of the patients.

Conclusions: Prasugrel and clopidogrel were associated with low rates of red thrombus after 36 weeks of dual-antiplatelet therapy after PCI. Stent coverage and yellow plaque classification were similar in prasugrel- and clopidogrel-treated patients.

Peri-strut contrast staining (PSS) is rarely observed after drug-eluting stent implantation and has the potential cause of stent thrombosis. A 68-year-old man with ST-elevation myocardial infarction (STEMI) underwent primary percutaneous coronary intervention (PCI) for a totally occluded left anterior descending artery. The lesion was successfully dilated with an everolimus-eluting stent. Ten months later, follow-up angiography revealed in-stent occlusion and revascularization was performed by drug-coated balloon (DCB) angioplasty. Another 12 months after the second PCI, PSS was found at the previous occlusion site. Optical frequency domain imaging (OFDI) was performed for the PSS lesion and showed malapposed stent struts with a protruded mass with irregular surface behind the stent struts, and coronary angioscopy also revealed completely exposed stent struts with an abutting yellow plaque. From these multimodality imaging findings, the possibility was assumed the pathogeneses of PSS, which is thrombus dissolution after stent under dilation for culprit lesion, and the progression of vessel ectasia under the condition of continuing inflammation after drug-eluting stent (DES) implantation and DCB angioplasty. DES implantation and DCB angioplasty for STEM I lesion may contribute to the development of PSS.