Comparison of Coronary Plaque Components between Non-Culprit Lesions in Patients with Acute Coronary Syndrome and Target Lesions in Patients with Stable Angina: Virtual Histology-Intravascular Ultrasound Analysis

Background and Objectives: The differences in plaque characteristics between non-culprit lesions (NCL) in acute coronary syndrome (ACS) patients (ACS-NCL) and target lesions (TL) in stable angina (SA) patients (SA-TL) are not well understood. We used a virtual histology- intravascular ultrasound (VH-IVUS) to compare the plaque components between ACS-NCL and SA-TL. Subjects and Methods: We compared VH-IVUS findings between 290 ACS-NCL and 276 SA-TL. VH-IVUS classified the color-coded tissue into four major components: green (fibrotic); yellow-green (fibro-fatty); white {dense calcium (DC)} and red {necrotic core (NC)}. Thin-cap fibroatheroma (TCFA) was defined as a $NC{\geq}10%$ of the plaque area in at least 3 consecutive frames without overlying fibrous tissue in the presence of ${\geq}40%$ plaque burden. Results: Although the plaque burden was significantly smaller ($52{\pm}13%$ vs. $54{\pm}14%$, p=0.044), ACS-NCL had a greater %NC area ($17.9{\pm}11.6%$ vs. $14.3{\pm}8.7%$, p<0.001) and %DC area ($9.7{\pm}9.8%$ vs. $8.1{\pm}8.0%$, p=0.032) compared with SA-TL at the minimum lumen site. By volumetric analysis, ACS-NCL had a greater %NC volume ($15.8{\pm}9.2%$ vs. $13.9{\pm}7.4%$, p=0.006) compared with SA-TL. TCFA was observed more frequently in ACS-NCL compared with SA-TL (27.6% vs. 18.1%, p=0.032). Independent predictors of TCFA by multivariate analysis were ACS {odds ratio (OR): 2.204, 95% CI: 1.321-3.434, p=0.021} and high-sensitivity C-reactive protein (OR: 1.101; 95% CI 1.058-1.204, p=0.035). Conclusion: Although the plaque burden was significantly smaller, ACL-NCL had more vulnerable plaque components compared with SATL, and ACS and high-sensitivity C-reactive protein were the independent predictors of TCFA.