Subclinical Carotid Atherosclerosis and Early Vascular Aging From Long-Term Low-Dose Ionizing Radiation Exposure A Genetic, Telomere, and Vascular Ultrasound Study in Cardiac Catheterization Laboratory Staff

OBJECTIVES This study sought to assess the association between long-term radiation exposure in the catheterization laboratory (cath lab) and early signs of subclinical atherosclerosis. BACKGROUND There is growing evidence of an excess risk of cardiovascular disease at low-dose levels of ionizing radiation exposure. METHODS Left and right carotid intima-media thickness (CIMT) was measured in 223 cath lab personnel (141 male; age, 45 +/- 8 years) and 222 unexposed subjects (113 male; age, 44 +/- 10 years). Leukocyte telomere length (LTL) was evaluated by quantitative reverse transcriptase polymerase chain reaction. The DNA repair gene XRCC3 Thr241Met polymorphism was also analyzed to explore the possible interaction with radiation exposure. The occupational radiological risk score (ORRS) was computed for each subject on the basis of the length of employment, individual caseload, and proximity to the radiation source. A complete lifetime effective dose (mSv) was recorded for 57 workers. RESULTS Left, right, and averaged CIMTs were significantly increased in high-exposure workers compared with both control subjects and low-exposure workers (all p values <0.04). On the left side, but not on the right, there was a significant correlation between CIMT and ORRS (p = 0.001) as well as lifetime dose (p = 0.006). LTL was significantly reduced in exposed workers compared with control subjects (p = 0.008). There was a significant correlation between LTL and both ORRS (p = 0.002) and lifetime dose (p = 0.03). The XRCC3 Met241 allele presented a significant interaction with high exposure for right side (p(interaction) = 0.002), left side (p(interaction) < 0.0001), and averaged (p(interaction) < 0.0001) CIMTs. CONCLUSIONS Long-term radiation exposure in a cath lab may be associated with increased subclinical CIMT and telomere length shortening, suggesting evidence of accelerated vascular aging and early atherosclerosis. (C) 2015 by the American College of Cardiology Foundation.