Abstract 4412: Coronary Plaque Characteristics of Thin-cap Fibroatheroma: An Intravascular Ultrasound and Optical Coherence Tomography Study
Background: Previous pathologic studies reported that the main mechanisms of acute coronary syndrome (ACS) are atherosclerotic plaque ruptures followed by thrombus formation. Therefore it is clinically important to identify plaques that are prone to rupture, known as thin-cap fibroatheroma (TCFA). The aim of this study is to evaluate plaque characteristics of TCFA using optical coherence tomography (OCT) in vivo.
Methods: After the successful treatment of culprit lesions, OCT and intravascular ultrasound (IVUS) examinations were attempted prospectively using motorized pullback in all 3 major coronary arteries for 41 ACS and 42 stable angina pectoris (SAP) patients. In 78 patients, 303 moderate or severe plaques (plaque/vessel area >50%) were identified somewhere other than on the culprit lesion (3.7 plaques per patient, range, 0 to 7). Qualitative OCT analyses for each focal atherosclerotic plaque were performed using the previously validated criteria. OCT criteria for TCFA was lipid-rich plaque (<90 degree) with fibrous cap thickness <65 microm. Remodelling index was calculated as the ratio of the lesion to the reference external elastic membrane area. Eccentricity index was calculated as (max-min)/max plaque thickness.
Results: Of 303 non-culprit plaques, 62 plaques matched OCT criteria for TCFA (20%). Most TCFAs were identified in patients with acute coronary syndrome (54/62). There was no significant difference in quantitative angiographic parameters between two groups. IVUS analyses were shown in the Table⇓. Multivariate analysis revealed that the independent predictors of OCT TCFA at non-culprit site were acute coronary syndrome (p<0.001), vessel size (p=0.005), and remodeling index (p=0.009).
Conclusions: OCT and IVUS analyses showed that TCFAs were identified in patients with ACS non-culprit segments, and had greater vessel area and larger remodeling index than non-TCFAs.