Radiation exposure during diagnostic testing for coronary artery disease (CAD) varies significantly between regions of the world, a new study shows. Patients in high-income countries are likely to be exposed to less radiation dose than patients in low- to low-middle income countries. Andrew J. Einstien, MD, PhD, of the NewYork-Presbyterian Hospital/Columbia University Irving Medical Center, New York, and colleagues from the U.S., U.K., India, Australia, Algeria, Italy, Turkey, Austria and the Philippines, discussed the corresponding data in a manuscript published online Wednesday in the Journal of the American Medical Association. CAD is becoming more common around the world. Several types of imaging are used to diagnose and manage patients with CAD, but along with imaging comes radiation. The International Atomic Energy Agency (IAEA) works within the United Nations to improve medical imaging and patient care around the world. The investigators in this study examined radiation exposure levels in this patient population using data from the IAEA. Radiation dose was measured across 742 centers in 101 countries in the INCAPS 4 (The IAEA Noninvasive Cardiology Protocols Study) trial. Patients included in this cross-sectional study underwent noninvasive CAD diagnostic testing during a single week in October through December 2023. CAD testing consisted of single-photo emission computed tomography (SPECT) or positron emission tomography (PET) nuclear cardiac imaging, cardiac computed tomography for coronary artery calcium scoring (CACS) or coronary computed tomography angiography (CCTA). Effective radiation dose in patients and the percentage of participating study centers that had a median effective dose of ≤ 9 mSv — the number recommended in current guidelines. A total of 19,302 patients (median age=63 years, 44% female) were included in the analysis. The median effective dose for CACS was 1.2 mSv, PET=2.0 mSv, SPECT=6.5 mSv and CCTA=7.4 mSv. More centers performed nuclear cardiology (81%) compared with CCTA (56%) (p<0.001) and more patients who underwent nuclear cardiology studies (79%) versus CCTA (56%) (p<0.001) had a median radiation dose of ≤ 9 mSv. Depending on where in the world patients underwent testing, radiation doses varied significantly for the same procedure. For example, patients had the lowest rates of radiation dose in Western Europe (median=4.8 mSv for nuclear cardiology, median=4.6 mSv for CCTA) and patients had the highest radiation dose for nuclear cardiology in Latin America (median=7.8 mSv) and the highest radiation dose for CCTA in Africa (median=25.2 mSv) (p<0.001 for all). The investigators wrote that during regression modeling, an inverse relationship was shown between country income levels and radiation dose: patients had lower levels of radiation in high-income countries and higher levels of radiation in low- and lower-middle-income countries. The dose for nuclear cardiology in low- to low-middle-income countries was 20% higher than high-income countries (95% confidence interval [CI]=3.6%-38.4%). For CCTA, patients in low- to low-middle-income countries had as much as 96% more radiation dose (95% CI=41.7%-170.8%) in CCTA compared with high-income countries. “This study highlights something we don’t often quantify so clearly — that where a patient lives can meaningfully influence their radiation exposure during routine CAD testing. The magnitude of regional variation, particularly for CCTA, is striking,” Giorgio A. Medranda, MD, Interventional Cardiologist at the St. Francis Heart Center at Good Samaritan University Hospital, Roslyn, New York, told CRTonline. Across all study regions, the investigators noted variation in radiation dose based on income levels. Investigators in this study demonstrated the regional and global differences in radiation protection for diagnostic imaging in CAD. These results point to a critical need for updated equipment and addressing radiation protection gaps. “As advanced imaging becomes more central to CAD diagnosis worldwide, radiation stewardship must be integrated as a core quality metric. Investment in training and standardized acquisition protocols until modern equipment can be made available is essential — especially in low- and middle-income countries where the disparity appears greatest,” Dr. Medranda said. “Invasive coronary angiography remains the diagnostic gold standard, and in many contemporary labs the radiation exposure of a straightforward diagnostic cath can be comparable to — or even lower than — poorly optimized CCTA protocols. The key issue highlighted here is not which modality is ‘better,’ but how well each is performed. In regions with older CT platforms or limited protocol optimization, the theoretical radiation advantages of CCTA may not be realized. Ensuring that imaging strategy aligns with available technology and expertise is essential to delivering high-value care.” Source: Einstein AJ, Williams MC, Weir-McCall JR, et al. Worldwide radiation dose in coronary artery diagnostic imaging. JAMA. 2026 February 25 (Article in Press). 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