Interventional cardiologists and nurses worry about cardiovascular disease developing in their patients. A study that looked at long-term radiation exposure to cath lab operators and staff may prompt them to add themselves to that list.
Maria Grazia Andreassi, MSc, PhD, of the CNR Institute of Clinical Physiology in Pisa, Italy, and colleagues designed the Healthy Cath Lab study to better understand the fundamental mechanisms involved in long-term exposure to low-level radiation by cath lab personnel. While other studies have explored occupational hazards such as orthopedic injuries, cataracts and cancers, they looked at the risk of developing early atherosclerosis with occupational doses of radiation.
They focused on three biomarkers for health risks: carotid intima-media thickness (CIMT), leukocyte telomere length (LTL) and a DNA repair gene polymorphism (XRCC3 Thr241Met). The Healthy Cath Lab study included 223 cardiac cath lab workers and 222 participants who were not exposed to occupational radiation as a control group. They used a case-control design to compare biomarkers from exposed and nonexposed participants.
A total of 57 cath lab staff had dosimetry data, from which they then estimated an occupational radiological risk score. In that group, the median individual effective dose was 19 mSv for interventional cardiologists and 7.1 mSv for nurses.
They found a borderline significant difference in CIMT between exposed and unexposed participants. But CIMT was significantly increased in cath lab staff with high exposure based on their occupational radiological risk score compared with the control group and low-exposure staff. They also noted a significant association between lifetime effective dose and left-side CIMT in the 57 workers with an occupational radiological risk score.
Compared with controls, exposed participants had significantly reduced LTL. A DNA analysis found significantly increased right-side, left-side and average CIMT in carriers of the Met241 allele vs. wild-type homozygotes. The carriers also had shorter LTL, but the finding was not significant.
“Long-term ionizing radiation exposure in a cardiac catheterization laboratory may be associated with increased subclinical CIMT and with telomere length shortening, suggesting evidence of early and accelerated vascular aging,” Andreassi et al wrote. They underscored the finding of left-side CMIT, noting that the left side of operators tends to be more exposed to radiation than the right side.
In an accompanying editorial, Charles E. Chambers, MD, of Penn State Hershey Medical Center in Hershey, Pa., pointed out that the cath lab workers had more risk factors for cardiovascular disease such as smoking and male sex, which could affect comparisons. The researchers had to use the occupational radiological risk score because so few of the cath lab staff had dosimetry data, and the finding of left-side CMIT was a comparison of controls and the 57 workers with a score.
“If the nurses in this study were not consistently at the table but also rotating throughout the room, the side variation is more challenging to interpret,” Chambers wrote. “However, these data in combination with the shortening of LTL is compelling as a potential marker for radiation injury.”
He called this occupational health risk a “personal liability” and encouraged manufacturers, hospitals, administrators and clinicians to tackle the issue in order to minimize occupational risk and prevent long-term harms.
The study and editorial were published in the April 20 issue of the Journal of the American College of Cardiology: Cardiovascular Interventions.