Does the ratio of eicosapentaenoic acid to arachidonic acid predict carotid intima-media thickness in the general population?

Abstract

Purpose: A decrease in the ratio of eicosapentaenoic acid (EPA) to arachidonic acid (AA) (EPA/AA) has been reported to be closely associated with increased incidence of cardiovascular diseases including coronary artery disease and stroke in subjects with high risk of atherothrombotic diseases. Similarly, an increase in the intima-media thickness (IMT) of the common carotid artery is a marker of early stage atherosclerosis and considered to be a predictor of cardiovascular disease. The present study was designed to investigate a possible relationship between the EPA/AA ratio and carotid IMT in the Japanese general population. Methods: A total of 401 participants (men=178, mean age=61.0 years), who visited our hospital for a yearly physical checkup from May 2010 to December 2010, were enrolled. In addition to a routine physical checkup program (routine physical examination, chest X-ray, electrocardiogram [ECG], and laboratory assessment of cardiovascular risk factors), EPA and AA were measured. Participants under medication with EPA were excluded from the study. An image of the common carotid artery was obtained by an ultrasound system and the mean IMT was calculated according to the guideline of Carotid Ultrasound Examination (Neurosonology 2006: 19(2):49-69). Cross-sectional analyses were performed to investigate a relationship between the EPA/AA ratio and carotid IMT. Results: Although the mean value of AA was not different in men and women, the EPA value and the EPA/AA ratio were significantly higher in men than in women (69.6±37.2 vs. 62.4±31.9 μg/ml, and 0.46±0.24 vs. 0.40±0.21, respectively). Strikingly, there was a positive correlation between the mean IMT value and the EPA/AA ratio in univariable regression analysis. However, in multivariable regression analysis, the mean IMT value was correlated with age, male gender, systolic blood pressure and ECG voltage, but not with the EPA/AA ratio. Both the EPA/AA ratio and the mean IMT value were greater in subjects with hypertension as compared to normotensive subjects. In contrast, the mean IMT, but not the EPA/AA ratio, was greater in subjects with than without diabetes mellitus. Conclusions: A decrease in the EPA/AA ratio does not predict increased carotid IMT in the Japanese general population. Significance of the EPA/AA ratio as a maker of clinical atherosclerosis should be further investigated in future by interventional studies.