Applied Radiology

Diagnosis

Malignant variant of anomalous RCA

Findings

Axial maximum-intensity projection (MIP) and parasagittal images from a computed tomography angiography (CTA) examination are provided. The axial MIP image demonstrates the right coronary artery (RCA) arising from the left coronary cusp just anterior to the origin of the left coronary artery (LCA). The parasagittal image demonstrates the RCA passing between the ascending aorta and the right ventricular outflow tract.

Discussion

Congenital anomalies of the coronary arteries are rare, occurring in approximately 1% of patients. Approximately 90% of these anomalies involve the origins of the coronary arteries with the remaining 10% representing coronary artery fistulas. The aortic valve normally has 3 cusps, including the left coronary cusp, which gives rise to the left main coronary artery, the right coronary cusp, which gives rise to the RCA, and the non-coronary cusp, which does not have an associated coronary artery. The LCA usually divides proximally into the left anterior descending coronary artery and the circumflex coronary artery. The origins of the coronary arteries should be perpendicular to the lumen of the aorta.

Many anomalies of the coronary arteries are incidental and of no clinical significance, but some may be symptomatic and can result in sudden cardiac death. There are 2 variants of an anomalous origin of the RCA, benign and malignant. The malignant variant is much more common with the RCA typically arising from the anterior aspect of the left coronary cusp between the origin of the LCA and the anterior commissure. The RCA then courses between the aorta and the pulmonary artery. The malignant nature of this variant is due to the fact that the artery travels between 2 high-pressure systems, which may compress the coronary artery, as well as the abnormal slit-like ostium of the RCA as it arises from the aorta at an abnormal angle. It is postulated that dilation of the aorta with exercise may result in further narrowing of the ostium. The benign course of the RCA travels posterior and inferior to the aorta.

Patients with the malignant variant of anomalous RCA may be asymptomatic or present with angina, myocardial infarction, or sudden death. Treatment consists of reimplantation of the anomalous vessel to the right coronary cusp in young patients. Older patients who have been asymptomatic may not need surgical treatment as the risk of sudden cardiac death appears to decrease with age.

• Dodd JD, Ferencik M, Liberthson RR, et al. Congenital anomalies of coronary artery origin in adults: 64-MDCT appearance. AJR Am J Roentgenol. 2007;188:W138-146.
• Datta J, White CS, Gilkenson RC, et al. Anomalous coronary arteries in adults: Depiction at multi-detector row CT angiography. Radiology. 2005;235:812-818.