Detection of plaque of saphenous vein graft by multidetector row computed tomography and comparison with gray-scale/virtual histology intravascular ultrasound

Application of virtual histological intravascular ultrasound in plaque composition assessment of saphenous vein graft diseases

OBJECTIVE

Saphenous vein grafts disease (SVGD) is a common complication after coronary artery bypass graft (CABG) and normally treated by percutaneous coronary intervention (PCI). The most common complication after SVG-PCI is slow or no-reflow. It is known that the no-reflow phenomenon occurs in up to 15% of the SVG-PCI and is associated with high risk of major adverse cardiac events (MACEs) and mortality, therefore, it is important to investigate the factors that could predict the clinical outcome of PCI for risk stratification and guiding interventions. In recent years, the spectral analysis of intravascular ultrasound (IVUS) radiofrequency data (virtual histology-IVUS [VH-IVUS]) has been used to provide quantitative assessment on both plaque compositions and morphologic characteristics.

DATA SOURCES

The PubMed, Embase, and Central databases were searched for possible relevant studies published from 1997 to 2018 using the following index keywords: "Coronary artery bypass grafting," "Saphenous venous graft disease," "Virtual histology-intravascular ultrasound," "Virtual histology-intravascular ultrasound," and "Percutaneous coronary intervention."

STUDY SELECTION

The primary references were Chinese and English articles including original studies and literature reviews, were identified and reviewed to summarize the advances in the application of VH-IVUS techniques in situ vascular and venous graft vascular lesions.

RESULTS

With different plaque components exhibiting a defined spectrum, VH-IVUS can classify atherosclerotic plaque into four types: fibrous tissue (FT), fibro fatty (FF), necrotic core (NC), and dense calcium (DC). The radiofrequency signal is mathematically transformed into a color-coded representation, including lipid, fibrous tissue, calcification, and necrotic core. Several studies have demonstrated the independent relationship between VH-IVUS-defined plaque classification or plaque composition and MACEs, but a significant association between plaque components and no-reflow after PCI in acute coronary syndrome. In recent years, VH-IVUS are applied to assess the plaque composition of SVGD, based on the similarity of pathophysiological mechanisms between coronary artery disease (CAD) and SVGD, further studies with the larger sample size, the long-term follow-up, multicenter clinical trials may be warranted to investigate the relationship between plaque composition of saphenous vein graft (SVG) by VH-IVUS and clinical outcomes in patients with SVGD undergoing PCI.

CONCLUSIONS

In degenerative SVG lesions, VH-IVUS found that plaque composition was associated with clinical features, future studies need to explore the relationship between VH-IVUS defined atherosclerotic plaque components and clinical outcomes in SVGD patients undergoing PCI, an innovative prediction tool of clinical outcomes can be created.

Intravascular ultrasound appearance of scattered necrotic core as an index for deterioration of coronary flow during intervention in acute coronary syndrome

In acute coronary syndrome (ACS) patients with deterioration of coronary flow during percutaneous coronary intervention (PCI), a scattered necrotic core pattern (SNC) is observed by intravascular ultrasound virtual histology (VH-IVUS). The purpose of this study was to evaluate the impact of SNC on deterioration of coronary flow during PCI in ACS. A total of 38 ACS patients were imaged using VH-IVUS before PCI. In addition to conventional definitions of thin-cap fibroatheroma by VH-IVUS (ID-TCFA), the SNC was defined as necrotic core foci with a maximum diameter of <14 pixels on a 400 × 400 VH-IVUS image in the presence of >50% plaque burden except in the ID-TCFA frame. Patients were divided into deterioration of coronary flow group (n = 15) and normal-reflow group (n = 23). The incidence of residual thrombus and plaque rupture, the external elastic membrane, plaque and fibrous volumes, the incidence of ID-TCFA and the average number of SNC per frame was significantly greater in deterioration of coronary flow group than in normal-reflow group (all parameters P < 0.05). Multivariate analysis revealed that the average number of SNC per frame was independently associated with deterioration of coronary flow in ACS patients (odds ratio 1.18, P < 0.05). In conclusion, an increased number of SNC is associated with deterioration of coronary flow during PCI in ACS patients.

Multidetector row computed tomography may accurately estimate plaque vulnerability: does MDCT accurately estimate plaque vulnerability? (Pro)

Over the past decade, multidetector row computed tomography (MDCT) has become the most reliable and established of the noninvasive examination techniques for detecting coronary heart disease. Now MDCT is chasing intravascular ultrasound (IVUS) in terms of spatial resolution. Among the components of vulnerable plaque, MDCT may detect lipid-rich plaque, the lipid pool, and calcified spots using computed tomography number. Plaque components are detected by MDCT with high accuracy compared with IVUS and angioscopy when assessing vulnerable plaque. The TWINS study and TOGETHAR trial demonstrated that angioscopic loss of yellow color occurred independently of volumetric plaque change by statin therapy. These 2 studies showed that plaque stabilization and regression reflect independent processes mediated by different mechanisms and time course. Noncalcified plaque and/or low-density plaque was found to be the strongest predictor of cardiac events, regardless of lesion severity, and act as a potential marker of plaque vulnerability. MDCT may be an effective tool for early triage of patients with chest pain who have a normal ECG and cardiac enzymes in the emergency department. MDCT has the potential ability to analyze coronary plaque quantitatively and qualitatively if some problems are resolved. MDCT may become an essential tool for detecting and preventing coronary artery disease in the future.