Measures of IMT and apoB/apoA-I may identify patients at high CV risk
MedWire News: Measures of carotid intima-media thickness (IMT) are significantly higher in hypercholesterolemic patients who carry a defective low-density lipoprotein-receptor (LDL-R) gene compared with their peers without the defect, shows study findings.
The researchers also found that in the group carrying the defective gene, the ratio of apolipoprotein (apo)B/apoA-I was a significant predictor of mean IMT.
The researchers say that high measures of IMT and the ratio of apoB/apoA-I may be useful for identifying hypercholesterolemic patients with the defective gene, and therefore be useful in diagnosing patients with high cardiovascular disease risk.
Lyudmila Vladimirova-Kitova and Tania Deneva-Koicheva (Medical University Plovdiv, Bulgaria) examined differences in the arterial wall structure and function of 250 newly detected, asymptomatic, severe hypercholesterolemic patients (aged >16 years) who were carriers (n=45) and noncarriers (n=205) of the defective LDL-R gene.
The team looked for mutations and polymorphisms in the LDL-R gene using denaturing gradient gel electrophoresis and DNA-sequencing techniques.
The researchers found no significant differences in levels of total cholesterol, LDL cholesterol, high-density lipoprotein (HDL) cholesterol, apoB, apoA-I, asymmetric dimethylarginine, homocysteine, or cellular adhesion molecules, between carriers and noncarriers of the defective LDL-R gene.
However, they did find significant differences between carriers and noncarriers in the estimate of the lifelong total vascular exposure to profound hypercholesterolemia (445.32 vs 395.35 mmol-year/l, respectively), and the apoB/apoA-I index (3.32 vs 2.48, respectively).
Furthermore, all measures of carotid IMT were significantly higher in participants with than without the defective LDL-R gene, and this difference remained after adjustment for age and gender.
Finally, the team found no significant differences with respect to the endothelium-dependent and independent FMD between the two groups, but backward selection identified the ratio of apoB/apoA-I as the most important factor related to the IMT mean in the group of carriers.
Writing in the journal Echocardiography, the researchers conclude that the apoB/apoA-I index could therefore be used as an accurate marker to select patients with a clinical diagnosis of family hypercholesterolemia who may benefit from screening for spot mutations and polymorphisms in LDL-R.
MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2011
By Nikki Withers