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Long-term radiation exposure in cath lab linked to subclinical atherosclerosis
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Cardiac catheterization laboratory staff with long-term exposure to low-dose ionizing radiation had increased carotid intima-media thickness and shorter leukocyte telomere length, potentially indicative of vascular aging and atherosclerosis, according to results of a new study.
The study included 223 cath lab personnel who participated in the Healthy Cath Lab study and 222 matched controls who had not been exposed to radiation.
Researchers measured left, right and averaged carotid intima-media thickness (CIMT) in 171 cath lab personnel and 156 controls. An occupational radiological risk score was calculated, according to proximity to the radiation source, caseload and the length of employment. Lifetime cumulative professional exposure was determined in a subset of 57 personnel.
The mean occupational exposure to ionizing radiation was 12.2 ± 8.3 years (range, 1-46). The estimated mean occupational radiological risk score was 18.5 ± 20. Among cath lab personnel with evaluable lifetime cumulative ionizing radiation exposure, the mean duration was 12.6 ± 8.6 years (range, 2-33) and the mean dose was 21.1 ± 26.3 mSv (range, 0.2-124).
Cath lab personnel with high levels of radiation exposure (n = 91) had significantly higher left, right and averaged CIMT compared with controls and cath lab personnel with lower degrees of radiation exposure (n = 80; P < .04 for all). Researchers observed a significant correlation between CIMT and occupational radiological risk score on the left side (r = 0.267; P = .001), but not on the right side. A similar correlation was reported for CIMT with lifetime effective dose on the left side (r = 0.379; P = .006), but not the right side.
Leukocyte telomere length, assessed via quantitative reverse transcriptase polymerase chain reaction, was significantly shorter among cath lab personnel exposed to ionizing radiation compared with controls (0.97 vs. 1.03; P = .008). The researchers reported a significant correlation between leukocyte telomere length and lifetime dose of radiation (r = –0.319; P = .03) and occupational radiological risk score (r = –0.267; P = .002). Multivariate analysis indicated that radiation exposure significantly and independently predicted risk for lower leukocyte telomere length (OR = 2.7; 95% CI, 1.5-4.9).
“It is noteworthy that a significant association with increasing radiation dose was found only on the left side, but not on the right, providing further support for a causal connection between occupational radiation exposure and early signs of subclinical atherosclerosis,” Maria Grazia Andreassi, MSc, PhD, from CNR Institute of Clinical Physiology, Pisa, Italy, and colleagues wrote.
The researchers also analyzed the XRCC3 Thr241Met polymorphism in 139 cath lab personnel to determine a potential link with exposure to ionizing radiation. Individuals with this polymorphism “might have a greater susceptibility to radiation-induced vascular effects,” the researchers wrote.
Among evaluable personnel, those with the Met241 allele had significantly greater CIMT on the right side (0.59 mm vs. 0.56 mm; P = .03) and left side (0.61 mm vs. 0.57 mm; P = .007) and averaged CIMT (0.6 vs. 0.57 mm; P = .006) compared with wild-type homozygotes. There was a significant interaction between the Met241 allele and an occupational radiological risk score > 11 on all three CIMT values (P = .002 for right side; P < .0001 for left side; P < .0001 for averaged CIMT).
“Future studies are warranted to better define the relationship between occupational radiation exposure and clinical manifestation of atherosclerotic disease to implement a better health surveillance,” Andreassi and colleagues concluded. – by Adam Taliercio
Disclosure: This research was partially funded by a grant from the Italian Ministry of Health. The researchers report no relevant financial disclosures.
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