Ultrasound Imaging of Carotid Intima-Media Thickness: an Office-Based Tool to Assist Physicians in Cardiovascular Risk Assessment

Can common carotid intima media thickness serve as an indicator of both cardiovascular phenotype and risk among black Africans?

BACKGROUND

It is not known whether common carotid intima media thickness (CIMT) can serve as a surrogate marker of cardiovascular risk among black Africans. Therefore, we examined whether CIMT differed significantly among individuals with distinct cardiovascular phenotype and correlated significantly with traditional cardiovascular risk factors in a black African population.

METHODS

CIMT was measured in 456 subjects with three distinct cardiovascular phenotypes - 175 consecutive Nigerian African stroke patients, 161 hypertensive patients without stroke and 120 normotensive non-smoking adults. For each pair of cardiovascular phenotypes, c-statistics were obtained for CIMT and traditional vascular risk factors (including age, gender, weight, waist circumference, smoking, alcohol, systolic and diastolic blood pressures, fasting plasma glucose, fasting total cholesterol). Pearson's correlation coefficients were calculated to quantify bivariate relationships.

FINDINGS

Bilaterally, CIMT was significantly different among the three cardiovascular phenotypes (right: p < 0.001, F = 33.8; left: p < 0.001, F = 48.6). CIMT had a higher c-statistic for differentiating stroke versus normotension (c = 0.78 right; 0.82 left, p < 0.001) and hypertension versus normotension (c = 0.65 right; 0.71 left, p < 0.001) than several traditional vascular risk factors. Bilaterally, combining all subjects, CIMT was the only factor that correlated significantly (right: 0.12 ≤ r ≤ 0.41, 0.018 ≤ p < 0.0001; left: 0.18 ≤ r ≤ 0.41, 0.005 ≤ p < 0.0001) to all the traditional cardiovascular risk factors assessed.

CONCLUSION

Our findings support CIMT as a significant indicator of both cardiovascular risk and phenotype among adult black Africans. However, specific thresholds need to be defined based on prospective studies.

Triglycerides-to-HDL ratio as a new marker of endothelial dysfunction in obese prepubertal children

OBJECTIVE

To investigate whether there is an association of the triglyceride-to-HDL cholesterol (TG:HDL-C) ratio with cardiovascular risk factors and early signs of vascular damage in obese prepubertal children.

DESIGN AND METHODS

In 50 obese (27 boys, 7.8±1.4 years) and 37 normal-weight (20 boys; 7.3±1.5 years) prepubertal children, anthropometric measurements, oxidative stress markers (urinary isoprostanes (PGF2α (prostaglandin F2α)), soluble receptor for advanced glycation end-products (sRAGE)) and insulin sensitivity (homeostasis model assessment of insulin resistance (HOMA-IR) and whole-body insulin sensitivity index (WBISI)) were evaluated. Lipids profile was assessed and the TG:HDL-C ratio was calculated. In addition, high-resolution ultrasound was performed to assess carotid intima-media thickness (cIMT).

RESULTS

Obese children showed significantly higher values of the TG:HDL-C ratio (1.9±1.1 vs 1.2±0.6, P=0.002) compared with controls. After dividing the population in tertiles of the TG:HDL-C ratio (<1.04, 1.04-1.67, >1.67), cIMT (P=0.0003), and HOMA-IR (P=0.0001) progressively increased from the lower to the upper tertile, whereas WBISI (P=0.0003) and sRAGE (P=0.05) progressively decreased. In a regression model, the TG:HDL ratio was significantly and positively associated with cIMT (r=0.493; P=0.0005). A cutoff point for TG:HDL-C ratio of 1.12 had 81% sensitivity and 49% specificity in the identification of children with cIMT values in the upper quartile (Area under the curve values from receiver operating characteristic curves=0.633±0.065, P=0.045).

CONCLUSION

This study confirms the reliability of the TG:HDL-C ratio as a useful marker of cardiovascular risk. Interestingly, our results underline that the TG:HDL-C ratio is directly related with early signs of vascular damage already present in prepubertal children.