Intra-atrial right coronary artery on dual-source CT: prevalence and characteristics

We aimed to determine the prevalence rate and radiological characteristics of intra-atrial right coronary artery (IARCA) in an adult population undergoing computed tomography coronary angiography (CTCA) on a dual-source CT scanner.

Overall, 7114 consecutive CTCAs acquired using a dual-source CT scanner in a high-volume, specialized cardiac care facility were retrospectively analyzed for the presence of IARCA. We scrutinized the CTCA datasets to determine the prevalence rate of IARCA and also to characterize its various imaging features including its length, depth from right atrial wall, segment involved, and presence and absence of atherosclerosis within the involved segment and in the rest of the right coronary artery (RCA).

The prevalence of IARCA was 0.29% (21/7114) in our study population. The mean length and depth of the intra-atrial segment was 14.85 mm and 2.57 mm, respectively. The mid-RCA was the most common segment to be involved, and no significant atherosclerosis was noted either in the intra-atrial segment or the rest of the RCA.

The prevalence rate of the incidental IARCA in the adult subjects undergoing CTCA is higher than previously reported for anatomical series, as seen in our study using a dual-source scanner. This under-reported anomaly must be explicitly assessed in patients undergoing ablative and other electrophysiological procedures, where it can have important implications.