Background: Apolipoprotein CIII (Apo CIII) is strongly atherogenic in patients with hypertriglyceridemia. However, it is not elucidated whether Apo CIII or triglyceride (TG) affects the vascular composition, in vivo, and is associated with plaque vulnerability.
Purpose: The aim of this study was to elucidate the relationship between plaque composition (PC), determined using virtual histology-intravascular ultrasound (VH-IVUS), and Apo CIII levels or TG levels. Moreover, we aimed to clarify whether the Apo CIII and TG system affects plaque vulnerability in patients with stable coronary disease (SCD).
Methods: We assessed PC using VH-IVUS in 116 consecutive patients with SCD before percutaneous coronary intervention (PCI). Fibrous (FI), fibro-fatty (FF), necrotic core (NC), and dense calcium (DC) regions were estimated to contribute to the volume of the entire culprit lesion. Blood examinations to determine plasma lipid and apolipoprotein levels (TG, low density lipoprotein cholesterol, high density lipoprotein cholesterol, Apo CIII, apolipoprotein B, and apolipoprotein A-I) were performed within 2 days, prior to PCI. The median Apo CIII level among the study patients was 8.5 mg/dL, and the patients were divided into a high Apo CIII group (HAC group, ≥8.5 mg/dL, n=57) and a low Apo CIII group (LAC group, ≤8.5 mg/dL, n=59).
Results: The Apo CIII level was higher in the HAC group than in the LAC group (12.489±0.432 mg/dL vs. 7.041±0.140 mg/dL, P<0.00001). Additionally, lesion length, plaque volume, and %NC volume were significantly higher in the HAC group than in the LAC group (lesion length: 72.488±4.426 mm vs. 51.651±3.754 mm, P=0.0008; plaque volume: 624.756±54.134 mm3 vs. 403.313±35.929 mm3, P=0.0006; and %NC volume: 17.576±0.749% vs. 15.416±0.594%, P=0.049). The %FI volume, %FF volume, and %DC volume were similar between the two groups. Interestingly, the %NC volume correlated with the Apo CIII level (r=0.226, P=0.015) and TG level (r=0.318, P=0.006). Moreover, Apo CIII strongly correlated with TG (r=0.760, P<0.00001). Additionally, the high-sensitivity C-reactive protein (hsCRP) level was significantly higher in the HAC group than in the LAC group (1840.930±413.492 ng/m vs. 1400.186±437.930 ng/ml, P=0.0104). Moreover, we defined patients, having an hsCRP level above the 3rd quartile level (1245 ng/ml) of hsCRP in all patients, as patients susceptible to coronary event (PSCE). Multiple logistic regression analysis revealed that TG was the only independent risk factor for PSCE (OR; 1.008, 95% CI; 1.001–1.0151, P=0.025).
Conclusion: The increase of plaque necrotic core in a lesion depends on the Apo CIII and TG levels. Furthermore, the Apo CIII and TG system might control the latent vulnerability of a stable plaque.