High yellow color intensity by angioscopy with quantitative colorimetry to identify high-risk features in culprit lesions of patients with acute coronary syndromes

Imaging of intracoronary thrombus

The identification of intracoronary thrombus and atherothrombosis is central to the diagnosis of acute myocardial infarction, with the differentiation between type 1 and type 2 myocardial infarction being crucial for immediate patient management. Invasive coronary angiography has remained the principal imaging modality used in the investigation of patients with myocardial infarction. More recently developed invasive intravascular imaging approaches, such as angioscopy, intravascular ultrasound and optical coherence tomography, can be used as adjunctive imaging modalities to provide more direct visualisation of coronary atheroma and the causes of myocardial infarction as well as to improve the sensitivity of thrombus detection. However, these invasive approaches have practical and logistic constraints that limit their widespread and routine application. Non-invasive angiographic techniques, such as CT and MRI, have become more widely available and have improved the non-invasive visualisation of coronary artery disease. Although they also have a limited ability to reliably identify intracoronary thrombus, this can be overcome by combining their anatomical and structural characterisation of coronary anatomy with positron emission tomography. Specific radiotracers which bind with high specificity and sensitivity to components of thrombus, such as activated platelets, fibrin and factor XIIIa, hold promise for the non-invasive detection of intracoronary thrombus. The development of these novel non-invasive approaches has the potential to inform clinical decision making and patient management as well as to provide a non-invasive technique to assess the efficacy of novel antithrombotic therapies or interventional strategies. However, these have yet to be realised in routine clinical practice.

Absence of coronary angioscopy-derived in-stent thrombi is associated with major bleeding events in acute myocardial infarction

BACKGROUND AND AIMS

The optimal duration of dual antiplatelet therapy for acute myocardial infarction is controversial because the bleeding risk outweighs the thromboembolic risk. We hypothesized that an in-stent thrombus (IS-thrombus) detected by coronary angioscopy (CAS) after stent implantation would be associated with high bleeding risk.

METHODS

This study included 208 patients who underwent CAS at 2 weeks after stent implantation for an acute myocardial infarction. The study was approved by the ethics committee at the Nihon University Itabashi Hospital (reference number RK-200714-10).

RESULTS

In 84 patients, in whom no IS-thrombus was identified in the culprit vessel using CAS, the major bleeding event rate was significantly higher than that in patients with IS-thrombi (n = 124). However, no difference was detected in major adverse cardiovascular events (MACE; stroke, hospitalization for a non-fatal myocardial infarction/unstable angina, target lesion revascularization, and cardiovascular death). After adjustments by the propensity score based on patient characteristics, the absence of IS-thrombi remained an independent predictor of major bleeding events (hazard ratio 4.73, 95% confidence interval 2.04-11.00, p < 0.001).

CONCLUSIONS

The absence of CAS-detected IS-thrombi in the subacute phase was independently associated with future major bleeding events, but not with MACE. These findings may help optimize the duration of dual antiplatelet therapy.

Color as an important biological variable in zebrafish models: Implications for translational neurobehavioral research

Color is an important environmental factor that in multiple ways affects human and animal behavior and physiology. Widely used in neuroscience research, various experimental (animal) models may help improve our understanding of how different colors impact brain and behavioral processes. Complementing laboratory rodents, the zebrafish (Danio rerio) is rapidly emerging as an important novel model species to explore complex neurobehavioral processes. The growing utility of zebrafish in biomedicine makes it timely to consider the role of colors in their behavioral and physiological responses. Here, we summarize mounting evidence implicating colors as a critical variable in zebrafish models and neurobehavioral traits, with a particular relevance to CNS disease modeling, genetic and pharmacological modulation, as well as environmental enrichment and animal welfare. We also discuss the growing value of zebrafish models to study color neurobiology and color-related neurobehavioral phenomics, and outline future directions of research in this field.

Coronary angioscopy: current topics and future direction

Disruption of vulnerable plaque and following thrombus formation are considered the main cause of acute coronary syndrome (ACS). Intracoronary angioscopy is an endoscopic technology that allows direct visualization of the coronary artery lumen and provides detailed information regarding plaque morphology in patients with coronary artery disease. The color and morphology of coronary plaque under angioscopy observation are proposed to be determinants for plaque stability. Angioscopically yellow plaque represents a thin-cap fibroatheroma, and is associated with a higher incidence of disruption and thrombus formation, and may be associated with future acute coronary syndromes. To circumvent the subjectivity of color interpretation, various quantitative methods have been proposed for identifying vulnerable plaques. Superior to other coronary imaging techniques such as VH IVUS and optical coherence tomography, angioscopy has impressively high sensitivity and specificity in detection of intraluminal thrombus. Angioscopy can also be used as an adjunctive technique during catheter intervention by directly visualizing the thrombus, stent struts and proliferating neointima. The time course and pattern of neointima coverage, as seen by angioscopy, various among different stent systems. Angioscopic assessment of serial changes after stent implantation may have potential benefits on patient's management after coronary stenting.

Coronary angioscopic evaluation for serial changes of luminal appearance after pharmacological and catheter interventions

Although preventive pharmacological therapies effectually reduce the risk of cardiovascular events, acute coronary syndrome (ACS) remains a leading cause of morbidity and mortality in our country, Japan. Disruption of atherosclerotic vulnerable plaques and flow-limiting thrombus formation in non-stent segments of native coronary arteries are considered a main mechanism of ACS. In addition, stent thrombosis originating from implanted metallic coronary stents, so-called vulnerable stents, occasionally appears as ACS in the clinical settings. Coronary angioscopy is a unique imaging modality permitting direct visualization of luminal structures, such as atherosclerotic plaque, thrombus, stent struts, and proliferating neointima. On the basis of accumulated angioscopic findings, intense yellow plaques and stents without neointimal coverage are considered vulnerable plaques and vulnerable stents, respectively. In contrast, morphological disappearance of vulnerable plaques or vulnerable stents by pharmacological and trans-catheter therapies imply stabilization of the plaques or stents. Hence, angioscopic assessment for vulnerability (or stability) of atherosclerotic plaques and implanted stents might be useful for risk classification in the future events of ACS. To evaluate serial changes of coronary lumen after pharmacological and catheter interventions using angioscopy might also provide important information on potential benefits and surrogate endpoints of the therapies and on patients' management.

Relationship between thin cap fibroatheroma identified by virtual histology and angioscopic yellow plaque in quantitative analysis with colorimetry

BACKGROUND

Thin cap fibroatheroma (TCFA) is considered to be a vulnerable plaque. Virtual Histology-intravascular ultrasound (VH-IVUS) can precisely identify TCFA in vivo. Intense yellow plaque on angioscopy determined by quantitative colorimetry with L a b color space corresponds with histological TCFA; in particular, a plaque of color b value >23 indicates an atheroma with a fibrous cap thickness <100 mum. In the present study, the relationship between VH-TCFA and angioscopic plaque color determined by colorimetry was investigated.

METHODS AND RESULTS

Fifty-seven culprit plaques in 57 patients were evaluated by VH-IVUS and angioscopy. VH-TCFA was defined as a plaque with a necrotic core >10% of plaque area without overlying fibrous tissue, and angioscopic TCFA was a plaque with b value >23. The frequency of angioscopic TCFA was higher in the VH-TCFA group than in the VH-non-TCFA group (74% vs 23%, P=0.0002). Moreover, yellow color intensity (b value) significantly correlated with plaque classification on VH-IVUS. When TCFA detected with angioscopy was used as the gold standard, the sensitivity, specificity, and accuracy for TCFA with VH-IVUS was 68%, 81%, and 75%, respectively.

CONCLUSIONS

VH-TCFA strongly correlated with angioscopic TCFA determined by a quantitative analysis with colorimetry.