Anomalous Origin of the Left Circumflex Coronary Artery from the Right Coronary Artery and the Left Anterior Descending Artery f

Various coronary artery anomalies have been described in the literature. We report an unusual case of anomalous coronary artery circulation that has not been described in the literature. Case Report. A 67-year-old female was admitted to our institution because of typical exertional angina. She was diabetic and hypertensive. Her physical examination was unremarkable except for high blood pressure and an irregular pulse. Electrocardiography revealed atrial fibrillation. Her transthoracic echocardiography was normal. The patient underwent coronary angiography. We were unable to selectively cannulate the left coronary artery, and nonselective injection disclosed no coronary artery arising from the left coronary sinus (LCS). On selective injection of the right coronary sinus (RCS), both the LAD and the RCA were found to originate from the same sinus with separate ostia, with the LAD originating from a more superiorly located ostium (Figure 1). It made a cranial anterior loop that indicated an anterior free wall course (Figure 2). The left circumflex (LCx) artery arose from the proximal RCA. The course of the RCA was normal, whereas the LCx had a retroaortic course (Figures 3 and 4). In the proximal course of the LCx there was a 50% stenosis. Given the small area supplied by the LCx, we decided to treat the patient conservatively. Her symptoms resolved with medical therapy including aspirin, atenolol, perindopril and simvastatin. Discussion. Adult coronary anomalies are not very common and are usually casual findings of diagnostic angiographic studies. The incidence of these anomalies has been reported to be between 0.29–1.34% of the population.^1–9 Coronary artery anomalies may involve anomalies of origin and course, anomalies of intrinsic coronary arterial anatomy, anomalies of coronary termination and anomalous collateral vessels.¹⁰ Anomalous origin of the LCx from the right coronary sinus (RCS) or proximal RCA is one of the most common forms of coronary artery anomalies. It has been reported in 0.17–0.45% of patients undergoing selective coronary angiography.^1–9,11 None of these series showed the LAD arising from the RCS in association with the LCx arising from the proximal RCA.^1–9,12 Instead, in all of the reported cases, the LAD was observed to arise from the LCS. In only one case,¹³ the coronary artery origin was exactly similar to our case, but the LAD had an intramyocardial course, as opposed to the anterior free wall course that was observed in our patient. The course of anomalously originating coronary arteries has been elegantly classified by Ishikawa et al.¹⁴ In cases where the LCx originates from either the RCA or the RCS, its course is always retroaortic. In our case, the LCx made a caudal posterior loop that indicated a retroaortic course as well. A coronary anomaly is known to be high risk when the anomalous artery originates ectopically from the opposite sinus and courses between the aorta and the pulmonary artery. In our patient, the LAD had an anterior free wall course and the course of the RCA was normal, whereas the LCx had a retroaortic course. Therefore, essentially no coronary artery coursed between the great vessels, making this unusual case a low-risk one. Regarding the association between atherosclerosis and coronary artery anomalies, an analysis from the Coronary Artery Surgery Study⁴ showed that anomalous circumflex coronary arteries had a significantly greater degree of stenosis than that in nonanomalous arteries in age- and gender-matched control patients (p = 0.02). Despite this difference, at 7 year there was no significant difference in survival by location or degree of stenosis in the anomalous artery.⁴ Taking this into consideration and given the small area supplied by the LCx, we decided to treat the patient conservatively and she did well on medical therapy. To our knowledge, this is the first report of a case with an unusual combination of coronary artery origin anomaly where the LCx originated from the proximal RCA, and the LAD from the RCS, and had an anterior free wall course.

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