Coronary Computed Tomography Angiography Evaluation of Plaque Morphology and Its Relationship to HDL and Total Cholesterol to HDL Ratio

Abstract

<h3>Lead Author's Financial Disclosures</h3> Nothing to disclose. <h3>Study Funding</h3> None. <h3>Background/Synopsis</h3> Traditionally non-high-density lipoprotein (non-HDL) indicators have been utilized to stratify cardiovascular risk. Population studies have demonstrated an inverse relationship between HDL cholesterol levels and cardiovascular risk, however, the mechanism by which HDL exhibits its protective effect on the cardiovascular system remains unclear. <h3>Objective/Purpose</h3> To investigate the relationship between the HDL-C level and the total cholesterol to HDL (TC/HDL) ratio with coronary artery plaque burden as determined by coronary computed tomography angiography (CCTA). <h3>Methods</h3> This is a cross-sectional study evaluating the association of HDL-C and TC/HDL ratio with coronary artery plaque volumes. We identified 190 subjects who had undergone quantitative plaque analysis and had lipoprotein values available at our institution. Plaque was analyzed quantitatively utilizing semi-automated plaque analysis software (QAngio version 2.0.5). The plaque volumes are presented as total atheroma volume normalized (TAVnorm). The HDL-C level and TC/HDL ratio were analyzed as continuous variables and categorized at clinically relevant levels. Multivariate regression models adjusted for cardiovascular risk factors were used to evaluate the association of HDL-C and TC/HDL ratio with coronary plaque volumes. <h3>Results</h3> The mean (SD) age of the 190 subjects was 58.9 (+/-9.8) years, and 63% were male. After adjustment for cardiovascular risk factors, HDL- C (>40mg/dL) is inversely associated with fibrous (p=0.003), fibrous fatty (p=0.009), low attenuation plaque (LAP) (p=0.014), total non- calcified plaque (TNCP)(p=0.003), and total plaque (TP)(p=0.005) volume but not associated with dense calcified plaque (p=0.229). TC/HDL ratio (>4.0) is directly associated with LAP (p=0.024) and not associated with fibrous, fibrofatty, TNCP, dense calcified plaque and TP volume. Notably, when examined as continuous variables, increasing HDL- C level is inversely associated with fibrous plaque, TNCP and TP volume and increasing TC/HDL ratio is directly associated with increasing fibrous plaque, and fibrous fatty plaque, LAP, TNCP and TP volume, independent of other risk factors. <h3>Conclusions</h3> There is a strong association between low HDL-C and increasing TC/HDL ratio with increasing coronary plaque volumes, independent of traditional risk factors of atherosclerosis. The findings of this study suggest mechanistic evidence supporting the protective role of HDL-C in coronary artery disease. Additionally, TC/HDL ratio offers value as a secondary treatment target beyond LDL-C, which is especially beneficial in individuals with prevalent lipid discordance, such as those with diabetes and metabolic syndrome.