Highlight
The HARRA randomized controlled trial reveals that the left radial artery approach (LRA) significantly reduces operator radiation exposure to the thorax, abdomen, and eyes compared to the uniform hyper-adducted right radial artery (HARRA) approach during diagnostic cardiac catheterization. The findings emphasize the importance of access site selection in minimizing occupational radiation hazard for interventional cardiologists.
Study Background and Disease Burden
Occupational radiation exposure remains a significant and adverse hazard for interventional cardiologists performing diagnostic and therapeutic cardiac catheterizations. Prolonged or repeated exposure to ionizing radiation can increase risks of cataracts, malignancies, and other radiation-induced injuries. While radial artery access for coronary procedures has become standard practice due to clinical benefits and patient comfort, operator radiation doses can vary based on the radial wrist used and arm positioning. The left radial artery (LRA) approach and the right radial artery (RRA) approach with uniform hyper-adduction (HARRA) are commonly used; however, comparative data quantifying operator radiation exposure between these approaches have been lacking. This trial addresses an important occupational safety gap by investigating real-time radiation exposure to key operator anatomical sites during diagnostic cardiac catheterization.
Study Design
The HARRA study was a single-center randomized controlled trial enrolling 534 patients scheduled for elective diagnostic cardiac catheterization. Participants were randomized to arterial access via the left radial artery (LRA, n=269) or a uniform hyper-adducted right radial artery (HARRA, n=265) approach. Inclusion criteria targeted elective cases suitable for either access site. Real-time radiation dosimeters were affixed to four operator locations: thorax, abdomen, left eye, and right eye, enabling cumulative and normalized radiation dose measurements during procedures. The primary endpoints were cumulative radiation exposure and radiation exposure normalized to patient dose-area product (DAP) at these four anatomical sites. Secondary variables included patient characteristics, anatomic factors such as subclavian tortuosity, catheter use, fluoroscopy time, and procedural metrics.
Key Findings
Baseline characteristics showed a higher prevalence of diabetes, prior coronary angiography, and distal radial approach utilization in the LRA group, while the HARRA group had significantly more subclavian tortuosity. Catheter use was greater in the LRA group. Despite these differences, key procedure-related variables such as DAP, fluoroscopy time, and contrast volume were comparable between groups.
Cumulative radiation exposure was significantly lower in the LRA group at all measured sites: thorax (9.66±8.57 μSv vs 12.27±7.09 μSv; P<0.001), abdomen (27.46±21.20 μSv vs 36.56±23.72 μSv; P<0.001), left eye (2.65±2.59 μSv vs 3.77±2.67 μSv; P<0.001), and right eye (1.13±1.69 μSv vs 1.44±1.62 μSv; P=0.01). Radiation exposure normalized to DAP similarly favored the LRA approach with statistically significant lower values at all sites except the right eye.
Multivariate linear regression analyses identified the HARRA approach as significantly associated with increased radiation exposure across all anatomical sites (all P<0.001). Subclavian tortuosity independently contributed to higher thoracic radiation doses. The distal radial approach correlated with lower abdominal radiation exposure, while increased catheter usage heightened radiation dose at thorax and eye sites.
Importantly, procedural complexity indicators such as fluoroscopy time, number of cineangiograms, and contrast quantity were not significantly different between groups, suggesting access-site-related positional factors rather than procedural intensity primarily drove radiation exposure variance.
Expert Commentary
This rigorously designed randomized trial provides compelling evidence that radiation exposure to interventional cardiologists during diagnostic cardiac catheterization differs by arterial access and arm positioning. The marked reduction in operator dose with the LRA approach likely reflects a favorable geometry reducing scatter radiation, especially given the more direct catheter path and less frequently encountered subclavian tortuosity.
The findings align with radiation physics principles, where arm and hand positioning influence the scattering environment and radiation beam orientation. The use of real-time dosimetry at multiple anatomical sites strengthens confidence in exposure assessment and highlights occupational risk particularly for radiosensitive areas such as the eyes.
While the distal radial approach was associated with reduced abdominal radiation doses, integration of this approach as part of standard practice requires further exploration, particularly regarding procedural feasibility and patient outcomes.
Limitations include its single-center design, potential crossovers, and baseline imbalances between groups that were adjusted statistically but may carry residual confounding. Nonetheless, these data reinforce current guideline statements advocating LRA as preferred radial access when feasible.
Conclusion
The HARRA study conclusively demonstrates that the left radial artery approach significantly reduces operator radiation exposure at critical anatomical sites compared to a uniform hyper-adducted right radial artery approach during diagnostic cardiac catheterization. Given the cumulative risks of occupational radiation, interventional cardiologists should preferentially consider the LRA approach to minimize radiation dose and enhance long-term operator safety. Future research may examine the impact of distal radial access and technological innovations in radiation shielding to further mitigate exposure risks.
References
Casazza R, Malik B, Hashmi A, Fogel J, Montagna E, Frankel R, et al. Operator Radiation Exposure Comparing the Left Radial Artery Approach and a Uniform Hyper-Adducted Right Radial Artery Approach: The HARRA Study. Circ Cardiovasc Interv. 2025 Apr;18(4):e014602. doi: 10.1161/CIRCINTERVENTIONS.124.014602. Epub 2025 Mar 19. PMID: 40104858; PMCID: PMC11995851.
Valgimigli M, Gagnor A, Calabró P, Frigoli E, Leonardi S, et al. Radial vs femoral access in patients with acute coronary syndromes undergoing invasive management: a randomized multicenter trial. Lancet. 2015;385(9986):2465–2476.
Lee MS, Agrawal N, Patel TM. Radiation Exposure to Operators in Interventional Cardiology: Techniques to Minimize Risk. Methodist Debakey Cardiovasc J. 2016;12(2):84–89.
Klein LW, Miller DL, Balter S, Laskey W, Haines DE, et al. Occupational health hazards in the interventional laboratory: time for a safer environment. Radiology. 2009;250(2):538–544.
