Radiation exposure after heart transplantation: trends and significance

Abstract

Background: Heart transplant recipients are frequently exposed to ionizing radiation from various imaging and cardiac procedures. However, radiation exposure carries various risks, including cancer. In this retrospective study, we calculated the mean cumulative radiation exposure during a 10-year period and the subsequent cancer risk after heart transplantation.

Methods: The study included all patients who underwent heart transplantation from August 1998 to July 2008 at our center. We identified all plain X-ray images, computed tomography, nuclear medicine procedures, and cardiac procedures (endomyocardial biopsies, right and left heart catheterization, and coronary angiograms) each patient underwent during the follow-up period. Radiation doses from cardiac procedures were the recorded exposures, and we used reference values for plain X-ray imaging and nuclear medicine procedures.

Results: The mean radiation dose was 84 mSv during the 10-year period, and cardiac procedures represented the largest radiation dose at 43.6 mSv (52%). The 10-year cumulative dose represented an additional 1 in 290 new cancers in the healthy population. Encouragingly, there was a decreasing trend of radiation exposure during the study period, with a mean decrease of 4.3 mSv per year.

Conclusion: Heart transplant patients are exposed to a 3.5 times greater dose of radiation per year compared with radiation from medical imaging in general population. The lifetime increase in cancer risk estimated from population studies was small. Although, there was a decreasing trend of radiation exposure during the study period, further reductions in radiation doses may be possible by the use of alternative imaging and non-imaging investigations.