Anomalous origin of the right coronary artery from the left coronary sinus with an interarterial course: Subtypes and clinical importance

Purpose: To classify anomalous origins of the right coronary artery (RCA) from the left coronary sinus (AORL) with an interarterial course into two subtypes and to evaluate the clinical importance of each. Materials and Methods: Institutional review board approval was obtained for this retrospective study, and informed consent was waived. Through a retrospective review of 22 925 consecutive cardiac computed tomographic (CT) scans, 124 cases of AORL with an interarterial course were identified. These anomalies were classified into two subtypes according to the location of the anomalous RCA ostium: high interarterial course (between the aorta and the pulmonary artery) and low interarterial course (between the aorta and the right ventricular outflow tract). The clinical records were evaluated, and differences in prevalence of typical angina and major adverse cardiac events (MACEs) between the subtypes were analyzed through the χ ² contingency tables or Fisher exact test. Results: After excluding patients with combined cardiac disease, 87 patients (51 [59%] men, 36 [41%] women; mean age, 56.0 years) were enrolled. Of the 87 patients, 53 had a high interarterial course and 34 had a low interarterial course. A significant difference in the prevalence of typical angina (high [43%] vs low [6%], P = .001 ) and MACE (high [28%] vs low [6%], P = .012) was observed between the two subtypes. For patients with a high interarterial course, the odds ratio for typical angina was 12.3 (95% confidence interval: 2.7, 56.6), and the odds ratio for MACE was 6.3 (95% confidence interval: 1.3, 29.7). Conclusion: The prevalence of typical angina and that of MACE were significantly higher in patients with a high interarterial course than in those with a low interarterial course.