Abstract 4716: Correlation Between Plaque Color Classification by Coronary Angioscopy and Fibrous Cap Thickness by Optical Coherence Tomography
Background: Yellow color intensity of coronary plaque evaluated by coronary angioscopy (CAS) might be associated with plaque vulnerability. Pathological studies have reported that vulnerable plaque have the thin cap fibroatheroma (TCFA) with a cap thickness of ≤65 μm. Optical coherence tomography (OCT) permit us to evaluate fibrous cap thickness, because OCT has higher resolution than intravascular ultrasound (IVUS), which resolution is approximately 10 to 20 times higher than IVUS.
Purpose: This study was undertaken to assess the relationship between plaque color evaluated by CAS and fibrous cap thickness estimated by OCT in patients with acute coronary syndrome (ACS).
Methods: 84 coronary artery plaques in 37 patients with ACS were observed with CAS and OCT. Plaque color was graded as grade 0 (white), grade 1 (slight yellow), grade 2 (yellow), or grade 3 (intensive yellow). TCFA was defined as a plaque with lipid content in ≥2 quadrants and the the thinnest part of the fibrous cap thickness<65ìm on the cross-sectional OCT image.
Results: The fibrous cap thickness estimated by OCT were 289±126μm in grade 0 (n=37), 154±46μm in grade 1 (n=14), 78±44μm in grade 2 (n=16), and 42±16μm in grade 3 (n=17) (p<0.001). There was a significant negative correlation between yellow color intensity and fibrous cap thickness (p<0.001, Figure⇓). The number of plaque with ≥2 quadrants were 0 (0%) in grade 0, 1(7.1%) in grade 1, 8 (50%) in grade 2, and 15 (88.2%) in grade 3 (p<0.001). TCFA was observed only in grade 2 (50%) and grade 3 (88.2%).
Conclusions: The plaque color in CAS was associated with the fibrous cap thickness which was assessed by OCT. TCFA was observed only in grade 2 and grade 3.