Biological effects of radiation exposure in patients treated with X-ray guided endovascular aortic repair

Abstract Background X-ray guided cardiovascular interventions such as endovascular aortic repair (EVAR) expose patients and operators to significant amounts of repeated ionising radiation over a long period of time. The biological effect of such protracted radiation exposure is poorly understood. We have previously demonstrated a higher incidence of dicentric chromosome (DC) aberrations in high-volume endovascular interventionalists and differences in acute DNA damage in lymphocytes between individuals following in vitro irradiation. Studies suggested a higher incidence of cancer in patients who underwent EVAR compared with those who have had open aneurysm repair, but the evidence is inconclusive. Further work is required to evaluate the biological radiation risk of X-ray guided cardiovascular interventions. Purposes We aimed to examine radiation-induced genome instability from patients after complex EVAR. We also aimed to investigate the intrinsic response of each patient to radiation using biomarkers of acute DNA damage following in vitro irradiation of their blood and to correlate this response to the expression of radiation-responsive genes. Methods Lymphocytes were isolated from patients after complex (branched/fenestrated) EVAR and non-irradiated controls. DC, a type of chromosomal aberration caused by radiation exposure were enumerated. γ-H2AX, a marker of acute DNA damage/repair, was measured by immunofluorescence after in vitro irradiation at 0.2 Gy and 1 Gy, along with the expression of the radiation-responsive genes FDXR, CCNG1, P21 and PHPT1 using qPCR. Results 17 patients (82% male, median age 73[59 – 85years]) and 16 controls (56% male, median age 68[53 – 83years]) were recruited. The mean incidence of DC was 3.782 (95% CI 3.13 - 4.43) and 0.898 (95% CI 0.48 -1.32) per 1000 cells for patients and controls, respectively (P<0.0001). Patients had higher background of γ-H2AX foci than unexposed controls, (0.7056, 95% CI 0.316 - 1.10) vs (0.241 95% CI 0.077 - 0.405) per cell, P<0.05. FDXR expression was most increased following irradiation (P<0.0001), reaching a mean 13.1-fold and 11.4-fold increase at 4-hour and 24-hour time-point, respectively, but this upregulation was not significantly different between the two groups. Conclusion We have shown an increased frequency of chromosomal aberrations in patients after complex EVAR, a biological finding that may support a propensity to developing malignancies. Patients also have higher basal DNA damage/repair (γ-H2AX) activity. Expression of ferredoxin reductase, FDXR gene could be a potential radio-responsive biomarker to provide personalised biological dosimetry information for clinical monitoring. Our study further underlines the long-term radiation risk of X-ray guided cardiovascular interventions and the potential of biological assays that may guide personalised care.