Apolipoprotein B levels may predict risk of future coronary artery disease (CAD) in young adults, according to findings from the CARDIA (Coronary Artery Risk Development in Young Adults) study, published in the Journal of American College of Cardiology.
Investigators analyzed lipid data from 2794 participants (mean age: 25 ± 3.6 years; BMI: 24.5 ± 5 kg/m2; 44.4% male), including apolipoprotein B (apoB) and year 25 (Y25) coronary artery calcium (CAC) score. At the beginning of the study, 27% were current smokers and 11.4% were obese.
Mean lipid values upon baseline examination were as follows: total cholesterol 177.3 ± 33.1 mg/dL; LDL-C 109.9 ± 31.1 mg/dL, non-HDL-C 124.0 ± 33.5 mg/dL; HDL-C 53 ± 12.8 mg/dL; apoB 90.7 ± 24 mg/dL; and median triglycerides 61 mg/dL. Four mutually exclusive concordant/discordant tertiles were formed from the apoB values, based on median apoB and LDL-C or non-HDL-C.
The middle and high apoB tertiles saw higher odds of developing Y25 CAC compared with the lowest tertile (middle odds ratio [OR]: 1.53; 95% confidence interval [CI]: 1.20-1.94 and high OR: 2.28; 95% CI: 1.79-2.89). High levels of apoB and low levels of LDL-C or non-HDL-C discordance were associated with Y25 CAC in adjusted models (OR: 1.55 and 1.45, respectively).
While BMI and obesity prevalence were higher than at baseline, there were no systematic trends across the 4 groups. There were also no significant differences in blood pressure (BP) or hypertension across groups.
When either LDL-C or non-HDL-C was high and apoB was low, the odds of CAC development were not higher than the referent and were in fact lower than the 2 tertiles with high apoB. Conversely, when either LDL-C or non-HDL-C was low and apoB was high, the odds of CAC development were significantly higher than in the 2 tertiles with low apoB.
“In this sample, differences in plasma TGs, BMI, dysglycemia, and BP across the discordance and concordance groups were modest and often fell within the normal ranges,” researchers wrote. “However, differences in the levels of apoB were already evident in young adulthood, and these differences were associated with the likelihood of prevalent coronary calcification in early midlife.”
Researchers concluded that “…measuring apoB as a marker of lipid-associated atherogenic risk may help identify young adults at risk for midlife coronary artery disease decades before adverse levels of traditional risk factors manifest, potentially providing opportunities for earlier intervention with lifestyle and possibly medication use in some individuals.”
Future studies are needed to confirm the associations of high apoB levels and clinical ischemic events during long-term follow-up.
Wilkins JT, Li RC, Sniderman A, Chan C, Llyod-Jones DM. Discordance between apolioprotein B and LDL-Cholesterol in young adults predicts coronary artery calcification: the CARDIA study. J Am Coll Cardiol. 2016;67(2):193-201. DOI: 10.1016/j.jacc.2015.10.005.