Relationship between radiation exposure and indicators of vascular resistance, arterial remodeling, and atherosclerosis.

Objectives: The diameter, resistance index (RI), and plaque formation in the common carotid artery (CCA) are indicators of arterial remodeling, vascular resistance, and atherosclerosis, respectively. This study used CCA parameters to investigate the longitudinal relationship between radiation exposure and vascular damage.

Methods: This retrospective cohort analysis included 806 atomic bomb survivors with estimated radiation doses from the Hiroshima atomic bomb survivor study database, who underwent carotid artery ultrasonography between April 2003 and December 2021. Participants were divided into three groups based on their radiation doses: <0.3 Gy, 0.3-3 Gy, and >3 Gy. The highest quartile of each index was defined as having a large CCA diameter, a high RI, increased plaque number, and a greater maximum plaque thickness.

Results: The median time between radiation exposure and carotid artery ultrasonography was 68.3 years. In the <0.3 and >3 Gy groups, the proportions of large CCA diameter were 24.2% and 50.0%, and the proportions of high RI were 23.5% and 54.6%, respectively. In multivariate analysis, the >3 Gy group had significantly larger CCA diameter (odds ratio [OR]: 4.36, 95% confidence interval [CI]: 1.30-14.7) and higher RI (OR: 4.04, 95% CI: 1.14-14.3) than the <0.3 Gy group. The plaque number or maximum plaque thickness did not differ significantly among the three-radiation dose groups.

Conclusions: Radiation exposure may affect vascular resistance and remodeling.

Advances in knowledge: To assess the risk of cardiovascular disease in radiation-exposed individuals, it appears necessary to investigate the effects of vascular damage other than atherosclerosis.