Coronary computed tomography angiography evaluation of plaque morphology and its relationship to HDL and total cholesterol to HDL ratio

Background While population studies have demonstrated that high density lipoprotein cholesterol (HDL-C) and the ratio of total cholesterol to HDL (TC/HDL) improve cardiovascular risk prediction, the mechanism by which these parameters protect the cardiovascular system remains uncertain. Objective To investigate the relationship between the HDL-C level and the total cholesterol to HDL (TC/HDL) ratio with the morphology of coronary artery plaque as determined by coronary computed tomography angiography (CCTA). Methods This is a cross-sectional study involving 190 subjects with stable coronary artery disease. Semi-automated plaque analysis software was utilized to quantify plaque and plaque volumes are presented as total atheroma volume normalized (TAVnorm). Multivariate regression models were used to evaluate the association of HDL-C and TC/HDL ratio with coronary plaque volumes. Results Of the 190 subjects the average (SD) age was 58.9 (9.8) years, with 63% being male. After adjustment for cardiovascular risk factors, HDL- C (>40 mg/dl) is inversely associated with fibrous (p = 0.003), fibrous fatty (p = 0.007), low attenuation plaque (LAP) (p = 0.007), total non-calcified plaque (TNCP) (p = 0.002) and total plaque (TP)(p = 0.004) volume. Furthermore, the TC/HDL ratio (> 4.0) is associated with fibrous (p = 0.047) and total non-calcified plaque (p = 0.039), but not with fibrofatty, LAP, dense calcified plaque, or TP volume. Conclusion There is a strong association between low HDL-C levels and increasing TC/HDL ratio with certain types of coronary plaque characteristics, independent of traditional risk factors. The findings of this study suggest mechanistic evidence supporting the protective role of HDL-C and the TC/HDL ratio's clinical relevance in coronary artery disease management.