Apolipoprotein CIII (Apo CIII) not only regulates triglyceride (TG) metabolism1 but also contributes to atherosclerotic formation and cardiovascular disease.2,3 However, it is unclear whether Apo CIII and TG affect vascular composition in humans and whether they are associated with plaque vulnerability. This study aimed to elucidate the relationship between plaque composition, determined using virtual histology-intravascular ultrasound (VH-IVUS), and Apo CIII and TG levels in 115 consecutive patients with stable coronary disease. We categorised patients, according to median Apo CIII level (8.5 mg/dL), into low Apo CIII (LAC group [≤8.5 mg/dL; n=59]), and high Apo CIII (HAC group [≥8.5 mg/dL; n=56]) groups and compared VH-IVUS findings between the two groups. Plaque vulnerability was estimated by measuring high-sensitivity C-reactive protein (hsCRP) levels in all patients, and the independent factor associated with plaque vulnerability was identified using lipids, including TG, low-density lipoprotein cholesterol, high density lipoprotein cholesterol, Apo CIII, apolipoprotein B, and apolipoprotein A-I.
Lesion length, plaque volume, and percentage necrotic core volume (assessed by VH-IVUS) were significantly greater in the HAC group than the LAC group. The hsCRP level was also significantly higher in the HAC group than the LAC group (1,861.464±420.424 ng/mL and 1,468.140±512.799 ng/mL, respectively; p=0.0104). Interestingly, the percentage necrotic core volume correlated with levels of Apo CIII (r=0.246; p=0.0079) and TG (r=0.289; p=0.0019). Moreover, Apo CIII levels strongly correlated with TG levels (r=0.731; p<0.0001).
We defined patients with hsCRP levels above the 3rd quartile level (1,245 ng/mL) as being susceptible to a coronary event (postsurgical cardiac event). Multiple logistic regression analyses revealed that TG was the only independent risk factor for a postsurgical cardiac event (odds ratio: 1.008; 95% confidence interval: 1.0010–1.0151; p=0.025). Our results suggest that Apo CIII and TG expand the necrotic core, contributing to the progression of plaque vulnerability in humans. Furthermore, compared with other lipids, TG, including the Apo CIII-TG system, are the most influential independent factors for latent vulnerability of a stable plaque.