Anomalous Right Coronary Artery Originated From Left Coronary Sinus With Interarterial Course: Evaluation of the Proximal Segment on Multidetector Row Computed Tomography With Clinical Correlation

Purpose: Anomalous origin of the right coronary artery (RCA) with an interarterial course is a potentially life-threatening anomaly. Clinical significance could depend on its orifice and interarterial course. We evaluated the anomalous RCA on multidetector row computed tomography (MDCT) with clinical correlation. Materials and Methods: Twenty-five electrocardiography-gated M DCT cases of 24 patients (mean [SD] age, 58.2 [12.3] years; 12 men and 12 women) with anomalous origin of RCA from left coronary sinus with an interarterial course were retrospectively reviewed in 3 hospitals. The cases were evaluated for the location of orifice, a takeoff angle from coronary sinus, mean diameters of RCA (orifice, interarterial, and reference), and the ratio of the diameters of RCA (orifice-reference and interarterial-reference) on MDCT with clinical correlation. Results: The orifice and the interarterial course of all anomalous RCAs were well visualized on MDCT. The narrowest portion of RCA was more frequent in the orifice (16/25 cases) than the interarterial course (6 cases). Three cases revealed the same diameter between the orifice and the interarterial course. The location of the orifice was not correlated with the diameters of anomalous RCA. Takeoff angles were correlated with the relative narrowing of the orifice of anomalous RCA (P = 0.001) and the relative narrowing of the interarterial course (P = 0.007). Only I patient showed significant luminal narrowing (>50% stenosis), and this patient showed a minimal takeoff angle and a persistent symptom. The symptom of this patient had disappeared after operation, and postoperative MDCT revealed an increased takeoff angle and no significant luminal narrowing. The other patients showed no significant luminal narrowing. Symptoms were not correlated with the takeoff angle and relative luminal narrowing (orifice-reference and interarterial-reference; P = 0.923, P = 0.915, and P = 0.703). Conclusions: The takeoff angles of anomalous RCA with an interarterial course are correlated with the relative narrowing of luminal diameters at the orifice and the interarterial course. Most cases show a benign nature. Evaluation of the proximal structure of anomalous RCA with an interarterial course could be important in a treatment plan.