Dual origin of the circumflex artery is an extremely rare anomaly. We report a rare case of a left circumflex artery arising from the left mainstem and an anomalous circumflex artery from a separate ostium in the right coronary sinus. Both these arteries supplied the circumflex territory. The potential pathological significance of the anomaly and pitfalls of the misdiagnosis are also discussed. J INVASIVE CARDIOL 2008;20:E54–E55

Case Report

Figure 2. RCA = right coronary artery; Anomalous Cx = anomalous circumflex artery originating near the right coronary ostium.

Figure 1. LMS = left mainstem; LAD = left anterior descending artery; LCX = left circumflex artery; OM1 = first obtuse marginal artery.

       A 62-year-old Caucasian male presented with recurring angina. He was experiencing angina attacks on walking 10 to 20 yards. The patient had suffered a myocardial infarction in the past and had undergone percutaneous intervention to his left anterior descending artery (LAD). Following the procedure, he remained relatively angina-free until recently. He was diabetic and hypertensive. There was a strong family history of premature coronary artery disease. He was unable to perform an exercise stress test due to peripheral neuropathy. In view of a positive history for coronary artery disease and multiple risk factors, we performed coronary angiography. The left mainstem had a normal origin and divided into the LAD and left circumflex (LCX) arteries (Figure 1). There was moderate in-stent restenosis, tight lesions in the first diagonal and major septal branch of the LAD. Surprisingly, from the right coronary sinus, there arose 2 arteries — a right coronary artery (RCA) and an additional circumflex artery (Figure 2). These arteries had separate ostia close to each other. Selective cannulation of the RCA delineated a lesion in the RCA (Figure 3). Both the RCA and anomalous circumflex arteries were diseased proximally with significant lesions. In view of the patient’s multivessel coronary artery disease, he was referred for coronary artery bypass graft surgery and successfully underwent the procedure.
Discussion

Figure 3. Selective cannulation of the right coronary artery showing the proximal stenosis.

       Coronary artery anomalies are rare. In a large series of 126,595 patients undergoing coronary angiography at the Cleveland Clinic,¹ the incidence of coronary anomalies was found to be 1.3%. A separate origin of the LAD and LCX was the most common anomaly, followed by a circumflex artery arising from the right sinus or the RCA. There was no report of duplication of blood supply to the circumflex territory in this large series. There has been only one other case of dual origin of a circumflex artery.² When our patient underwent percutaneous coronary intervention a few years back, right coronary injection did not demonstrate an anomalous circumflex, perhaps due to selective cannulation of the RCA. On this occasion, however, when we attempted to cannulate the RCA, we engaged the anomalous circumflex artery and opacified the RCA (Figure 2). Subsequently, we selectively cannulated the RCA (Figure 3). Our case illustrates that an anomalous circumflex can be missed if it arises from a separate ostium close to the RCA ostium.
       The anomaly described here is extremely rare and is benign.1 In a study by Wilkins,³ 71% patients with an anomalous circumflex artery had significant coronary atherosclerosis in the proximal portion of anomalous vessel. An analysis from the Coronary Artery Surgery Study⁴ showed that anomalous circumflex arteries had a significantly greater degree of stenosis than normal arteries. In cases where the anomalous circumflex originates from either the RCA or the RCS, its course is always retro-aortic.⁵ The posterior course of the anomalous circumflex coronary artery may predispose this vessel to atherosclerosis in patients with coronary disease. Our patient had significant stenosis in the anomalous circumflex artery. Although a benign anomaly, it is important to inform the surgeons so as to avoid accidentally cross-clamping or transecting the artery during surgery.