Relationship Between Thin Cap Fibroatheroma Identified by Virtual Histology and Angioscopic Yellow Plaque in Quantitative Analysis With Colorimetry

Abstract

he major cause of acute coronary syndrome (ACS) is disruption of an atherosclerotic plaque and the subsequent formation of a thrombus. 1 Pathological examinations have revealed that thin cap fibroatheroma (TCFA) is frequently found in patients who die of ACS, and plaque rupture usually occurs in a lesion with an abundant necrotic core and an overlying thin fibrous cap. [2][3][4] Recently, a spectrum analysis of intravascular ultrasound (IVUS)-derived radiofrequency data based on a pathological analysis has demonstrated more detailed quantitative information on plaque composition and morphology than a gray-scale analysis. 5-8 TCFA identified by Virtual Histology (VH-TCFA) are recognized more frequently in patients with ACS than in those with stable coronary artery disease. 6,8 Similarly, several coronary angioscopic studies have demonstrated that yellow plaques are commonly observed at the culprit lesion of ACS. 9-13 Furthermore, quantitative evaluation of the yellow plaque could be available with newly developed software using L*a*b* color space. [13][14][15][16] Angioscopic examination of ex vivo human tissue samples has indicated that a coronary plaque with high-intensity, yellow color regions (b*value >23) consists of lipid cores beneath a TCFA (fibrous cap thickness <100 μm). 15 However, there is no available comparison of plaque classification determined by VH-IVUS and by angioscopic findings. The present study investigated the characteristics of VH-TCFA in comparison with the angioscopic yellow color intensity as determined by quantitative colorimetry. Methods Patient SelectionInitially, we enrolled 67 patients who had a definable culprit plaque on pre-interventional IVUS and coronary angioscopic examinations. Ten disrupted plaques including ulceration on IVUS or massive thrombi on angioscopy (thrombus area ≥50% of visual field) in 10 patients were excluded because the VH analysis may have provided unreliable tissue characterization and no established algorithm for thrombus. Finally, 57 plaques in 57 patients were analyzed. The Medical Ethics Committee at Chiba-Hokusoh Hospital approved this study, and written informed consent was given by all patients before participation. Clinical DemographicsThe clinical data and information about clinical presentation were based on chart reviews. Stable angina pectoris (SAP) was defined as a positive stress test and no change in the frequency, duration or intensity of chest symptoms within 4 weeks. In each patient, the culprit lesion was identified by a combination of electrocardiographic findings, (Received August 18, 2008; revised manuscript received October 5, 2008; accepted October 24, 2008; released online January 16, 2009

Intense Yellow Culprit Plaque Coloration is Closely Associated with Troponin-T Elevation and Flow Complications Following Elective Coronary Stenting

“…Intense yellow plaques upon angioscopic examination correlated with the presence of a plaque with a large lipid area on IB-IVUS display 14) . Postmortem histological assessment and in vivo studies with other coronary imaging devices, such as virtual histology IVUS and OCT, have shown that yellow color intensity is associated with a lipid core underneath a thin fibrous cap and that intense yellow plaques might be structurally vulnerable [15][16][17] . Similarly, it has been reported that nonintense yellow plaque was plaque with a thick fibrous cap 17) .…”

“…Combination study with angioscopy and gray-scale IVUS showed that the presence of yellow plaques is correlated with positive remodeling of coronary arteries 22) . Therefore, intense yellow plaques, which are partly equivalent to thin-cap fibroatheromas identified by OCT or IVUS [15][16][17] , may have a large plaque burden. Also, diffuse long lesions possibly have a large plaque burden since long stent implantation as well as stenting for intense yellow plaques may cause post-procedural myocardial injury.…”

What Does the Yellow Color of Angioscopy Mean? Why Yellow Plaque Is Always Vulnerable?

“…Their system can consistently measure yellow plaque color independent of such conditions as light intensity, the distance from the lens of angioscope to the objective, and the angle of the angioscope to the region of interest, after proper adjustments for brightness (L * value is within 42) and are strongly correlated with the thin cap fibroatheroma determined by Virtual Histology-IVUS. 43) The plaques of b * value >23 are associated with elevated malondialdehyde-modified low-density lipoprotein levels 44) , which has been reported to be detected in the plasma of patients with ACS.…”

Coronary Angioscopic Evaluation for Serial Changes of Luminal Appearance After Pharmacological and Catheter Interventions

“…[8][9][10][11][12][13][14][15][16] The majority of yellow plaques are composed of lipid-rich tissue or necrotic core identified by optical coherence tomography (OCT) and radiofrequency intravascular ultrasound (IVUS). [10][11][12][17][18][19] In contrast, white plaque is histological fibrous plaque or lipid plaque with thick fibrous cap. 11,[17][18][19] Yellow intensity is negatively correlated with fibrous cap thickness, and intense yellow plaque is corresponded to TCFA.…”