By Binita Shah
Cumulative radiation exposure to both patients and operators has become a topic of great interest given the overall increased use of both cardiovascular and non-cardiovascular imaging modalities. This is all the more important with the increasing usage of multimodality imaging, including non-invasive (single-photon emission computed tomography, computed tomography angiography) and invasive procedures in patients with known or suspected coronary artery disease.
The risks of increased radiation exposure, in the short run, include dermatologic burns for patients and, in the long run, increased risk of malignancy for both patients and operators.
At the same time, there is a growing trend to perform invasive coronary procedures utilising the transradial approach due to decreased major bleeding complications and increased patient satisfaction compared with the transfemoral approach. However, there is a learning curve for transradial approach for coronary angiography and intervention, and it is associated with longer procedural and fluoroscopy times. Whether the increased risk of radiation exposure is seen in transradial compared with transfemoral cases when procedures are performed by experienced operators is less clearly defined.
A retrospective analysis of radiation exposure during coronary angiography via transradial versus transfemoral approach performed by experienced operators at the New York University Langone Medical Center was presented on 15 May during an oral abstract session of the 2012 EuroPCR meeting. In a contemporary cohort of 1,696 patients undergoing coronary angiography with or without percutaneous coronary intervention (PCI) by experienced operators, transradial approach was associated with higher radiation exposure when compared with transfemoral approach. Experienced operators were defined as operators performing more than 75 PCIs per year for at least five years with more than 95% of cases using one type of approach to access.
In the diagnostic coronary angiogram only cohort, the main measure of radiation exposure, dose area product (DAP), was significantly 20.3% higher in the transradial compared with the transfemoral approach group. Junior cardiology fellows meaningfully participate during diagnostic procedures, and, therefore, a sensitivity analysis was performed excluding cases with a junior fellow present. Although median DAP decreased by 3.9% in the transradial and 0.6% in the transfemoral approach group, radiation exposure still remained significantly higher with transradial approach when the analysis was limited to procedures performed by very experienced operators without a junior cardiology fellow present.
In the PCI cohort, the majority were elective cases undergoing ad-hoc PCI with very low complication rates in both groups. Although lesion and procedural characteristics were well-balanced between the transradial and transfemoral approach groups, DAP was significantly 27.6% higher in the transradial compared with transfemoral approach groups.
Although this is a retrospective analysis of a single centre experience, we demonstrate that even in the hands of experienced operators, the radiation exposure still remains higher when using transradial approach compared with transfemoral approach. This study is also one of the few large cohorts to focus on a group of experienced operators and measure DAP, a better estimate of patient radiation dose than fluoroscopy time, as the primary outcome of interest. While transradial procedures may have other advantages (reduced access site complications/bleeding), the amount of radiation administered should also be considered with this approach.
Binita Shah is an interventional cardiologist, New York University School of Medicine, New York, USA