Comparison of the radiation dose between dual-acquisition coronary computed tomography angiography and coronary angiography for coronary spasm

Background: Coronary computed tomography angiography (CCTA) is an imaging technique that can be used to evaluate and diagnose coronary artery stenosis. Dual-acquisition CCTA (DA-CCTA) with additional nitrate infusion is a promising alternative noninvasive diagnostic tool, as conventional CCTA has limitations in the diagnosis of variant angina compared to conventional angiographic coronary spasm tests. However, DA-CCTA may pose a potential risk due to radiation exposure. We compared the radiation dose between DA-CCTA and the coronary angiographic spasm provocation test.Methods: Patients with clinically suspected variant angina at a single hospital between March 2013 and October 2018 were screened and underwent DA-CCTA or a coronary angiographic spasm provocation test. The effective radiation dose required for each approach was compared. Results: In total, 211 suspected variant angina patients underwent DA-CCTA or the coronary angiographic spasm provocation test. Of these, 49 patients (mean age, 59.8 years; 67.3% men) received DA-CCTA and 162 patients (mean age, 60.5 years; 66.2% men) received a coronary angiographic spasm provocation test. There was a significant difference in the effective radiation dose, with a median dose of 5.1 mSv (interquartile range [IQR], 4.1–9.2 mSv) required for DA-CCTA and a median dose of 10.9 mSv (IQR, 8.4–15.2 mSv) for the coronary angiographic spasm provocation test (p<0.001).Conclusion: DA-CCTA showed a significantly lower effective radiation dose than the coronary angiographic spasm provocation test required to diagnose variant angina.