The changes of individual carotid artery wall layer by aging and carotid intima-media thickness value for high risk

Aim: It is still unclear which layer (intima or media) is mainly involved in increased carotid intima-media thickness (CIMT) by aging and also unclear regarding CIMT value suggesting high cardiovascular risk, although 75th percentile value of CIMT is known as a high risk in asymptomatic adults. We sought to find the changes of carotid intima thickness (CIT) and carotid media thickness (CMT) by aging and the 75th percentile value of CIMT in asymptomatic Korean adults. Method: This is an observational cohort study. Carotid ultrasound findings (n=2204 from 12 hospitals) were prospectively collected. The carotid images were sent to Korea Research Institute of Standards and Science for analysis using specialized software which can measure intima and media wall also. Results: Mean age was 58.1 +/- 13.5 years old (52% of men). Pearson's correlation coefficient between age and right CIMT (r=.489, P<.001) and right CMT (r=.482, P<.001) was higher than that between age and right CIT (r=.284, P<.001). Mean right CIMT in male and female was 0.696 +/- 0.163 and 0.686 +/- 0.167 mm (P=.180), and the 75 percentile value was 0.778 and 0.771 mm, respectively. Mean right CIT was 0.311 +/- 0.069 and 0.303 +/- 0.064 mm (P=.009), and mean right CMT was 0.391 +/- 0.124 and 0.388 +/- 0.131 mm (P=.694) in male and female, respectively. Left carotid ultrasound findings showed similar to the right one. Conclusion: An increased CIMT by aging was mainly due to increased CMT rather than CIT in asymptomatic adults. The 75th percentile values of right CIMT were 0.778 and 0.771 mm in asymptomatic Korean male and female adults, respectively.