High Yellow Color Intensity by Angioscopy With Quantitative Colorimetry to Identify High-Risk Features in Culprit Lesions of Patients With Acute Coronary Syndromes

High yellow color intensity (HYCI) regions of atherosclerotic plaque, determined by angioscopy with quantitative colorimetry, are associated with lipid cores underneath thin fibrous caps in ex vivo tissue samples. To determine whether HYCI regions of coronary plaque are associated with disruption or thrombus in living patients, quantitative colorimetry was applied to angioscopy, and the color of culprit lesions was measured in patients with acute coronary syndromes. In 46 patients with acute coronary syndromes (acute myocardial infarction, n = 14; unstable angina pectoris [UAP] with culprit thrombus, n = 16; and UAP without culprit thrombus, n = 16), the recorded angioscopic images of culprit lesions were analyzed using a quantitative colorimetric method based on the L*a*b* color space applied to angioscopy (positive b* = yellow color intensity). HYCI was defined as b* value >23. Plaque disruption was significantly more prevalent in 19 of 24 HYCI regions (79%) than in 9 of 22 non-HYCI regions (41%) (p = 0.007). Culprit HYCI regions were prevalent in patients with myocardial infarction (11 of 14 [79%]), followed by those with UAP with thrombus (9 of 16 [56%]) and UAP without thrombus (4 of 16 [25%]) (p = 0.01 for trend), and were significantly more prevalent in 66% of patients with myocardial infarction and UAP with thrombus compared with 25% of those with UAP without thrombus (p = 0.007). In conclusion, HYCI regions of coronary plaque may be indicative of high-risk lesions vulnerable to thrombosis. Coronary angioscopy with quantitative colorimetry could be used to study the association between high-risk coronary lesions and future cardiovascular events.