Congenital Absence of Left Circumflex Coronary Artery: Role of Computed Tomography Coronary Angiography

Full Article

PR Kapur, R Jain, GP Vashist

Hong Kong J Radiol 2014;17:e1-4

DOI: 10.12809/hkjr1412126



Congenital coronary artery anomalies are infrequently seen during coronary angiography, and are usually diagnosed incidentally. Among such anomalies, absence of the left circumflex artery is extremely rare. We report on a 49-year-old man who presented with a 2-month history of increasing exertional breathlessness and was found to have poor left ventricular function on echocardiography. Routine coronary angiography showed a normal left anterior descending, no left circumflex artery and a dominant right coronary artery. Neither aortography nor pulmonary angiography showed a separate ostium for the left circumflex artery. Multi-detector computed tomographic coronary angiography was performed to confirm the diagnosis of congenital absence of the left circumflex artery.




PR Kapur、R Jain、GP Vashist




Congenital absence of the left circumflex artery (LCX) is very rare; only a few case reports exist in the literature. In most patients, this is discovered incidentally during imaging studies like coronary angiography, and most are asymptomatic.1 However, association with vasospastic angina, infarction, and systolic click syndrome have been described, which may be life-threatening.2 3 4 We report the case of a 49-year-old male who presented with recent worsening of dyspnoea on exertion and was found to have poor left ventricular function on echocardiography. Routine coronary angiography showed a normal left anterior descending (LAD) artery, no LCX, and a dominant right coronary artery (RCA). Neither aortography nor pulmonary angiography showed a separate ostium for the LCX. A dilated left atrium and left ventricle with left ventricular ejection fraction of 36% were noted.


Multi-detector computed tomography (MDCT) was performed to confirm the diagnosis. To the best of our knowledge this is a second report of its kind, in which this anomaly was associated with myopathy. In such cases, precise morphological and functional evaluation is warranted to guide treatment and gauge the prognosis.



A 49-year-old man with known chronic obstructive pulmonary disease presented with a 2-month history of increasing breathlessness on exertion in May 2011. He did not have diabetes or hypertension. Physical exam-ination revealed a well-nourished male with a pulse rate of 72 beats/min, blood pressure of 100/80 mm Hg, and peripheral arterial oxygen saturation of 98%. Peripheral pulses were normal. Routine investigations yield no significant lipid profile abnormality. Cardiac auscultation revealed regular heart sounds and a left ventricular third sound (S3). His chest X-ray showed no abnormality. His 12-lead electrocardiogram showed left axis deviation and two-dimensional echocardiography revealed global hypokinesia with a dilated left atrium and left ventricle, and a left ventricular ejection fraction of 36%.


Selective coronary angiography via the radial artery approach revealed the left main and LAD coronary arteries that appeared normal, and their small-sized diagonal vessels showed 50% and 70% mid and ostial stenoses, respectively. The RCA was a large super dominant vessel which crossed the left atrioventricular (AV) groove and supplied the inferior and posterolateral walls of the left ventricle, but showed no discrete stenosis. The LCX was not visualised. Aortic root and pulmonary angiography did not reveal any anomalous coronary artery. A nuclear-medicine myocardial perfusion scan with Thallium-201 was normal. However, angiography using a 64-slice MDCT performed on the following day confirmed absence of the LCX. The posterior descending artery and posterior left ventricle (PLV) were prominent; the PLV supplied the posterolateral wall of the left ventricle (Figures 1, 2, 3).

Figure 1. A volume-rendered image of heart demonstrates absence of the left circumflex artery in the left atrioventricular groove (black arrow) with the left main artery (LMA) continuing as left anterior descending artery (LAD).


Figure 2. The angiographic views of the heart (maximum intensity projection) show absence of the left circumflex artery and a superdominant right coronary artery (arrows), with large posterolateral branches perfusing the postero-lateral and lateral walls of the heart (usually supplied by the left circumflex artery).


Figure 3. A volume-rendered image of the heart demonstrates a good-sized right postero-lateral ventricular branch crossing the crux of the heart and then ascending into the inferior part of atrioventricular groove (arrow), and supplying the postero-lateral and lateral walls of the heart (usually supplied by the left circumflex artery).



Congenital coronary artery anomalies are seen rarely, and have been reported to occur in 0.64% to 1.3% of patients undergoing angiography.1 5


Congenital absence of the LCX is a vascular anomaly in which the artery fails to develop in the AV groove.6 7 8 Yamanaka and Hobbs1 found it in only four of 126,595 patients who underwent coronary angiography between 1960 and 1988, yielding a frequency of only 0.003% in all the patients, and 0.24% in those with other coronary artery anomalies. Separate origins of the LAD and LCX from the left sinus of valsalva were the most common anomalies, and occurred in about 0.41% of the patients studied. Anomalous origin of the LCX from the right sinus of Valsalva or the RCA was reported by Ueyama et al6 and Page et al9 with a frequency of 0.39% and 0.67%, respectively. Ott et al10 reported a rare patient with an ectopic LCX originating from the right pulmonary artery.


In 1984, Bestetti et al11 described the first autopsied case of congenital absence of the LCX in a 12-year-old girl clinically diagnosed as having idiopathic cardiomyopathy. The coexistence of the two conditions was postulated to be incidental. To the best of our knowledge, ours is the second report of an absent LCX and dilated cardiomyopathy in the world literature.


There could be an association between the two conditions in patients with coronary artery hypoplasia (which could occur with an absent LCX and poorly developed RCA) that may give rise to myocardial fibrosis due to chronic ischaemia in the area of myocardial hypoperfusion and lead to a dilated cardiomyopathy.12 However, in the case reported by Bestetti et al,11 the pathological findings did not support any such association. In our patient too, cardiomyopathy also appears to be incidental, as myocardial perfusion imaging showed nil normal. The degree of stenosis in the minor vessels of our patient cannot account for the global hypokinesia and poor left ventricular function.


Conventional cardiac catheterization is a well-known modality for the detection of coronary anomalies. However, MDCT is emerging as an essential imaging tool for this purpose, as many congenital coronary anomalies are more easily assessed using this modality.13 Notably, MDCT is well suited to detect and define the anatomical course of coronary artery anomalies and their relationship to other cardiac and non-cardiac structures, because of the three-dimensional nature of the images it provides. This makes CT angiography an imaging modality of choice for the investigation of known or suspected coronary artery anomalies.14

With CT arteriography, the frequency of this anomaly can be more accurately assessed but might not yield a particularly high frequency. Komatsu et al15 reported only two cases of this type of anomaly in their 3910 consecutive cases undergoing MDCT, yielding a frequency of 0.05%. This suggests the anomaly remains very rare, even in the era of refined investigations.


Recognition of this anomaly is important, as it may mimic atherosclerotic coronary artery disease, whereby oxygen demand in myocardium normally supplied by it are taken over by RCA and such supply may not be sufficient during increased physical activity.



Although the absence of a LCX is considered benign, its clinical relevance cannot be overlooked, as it has been associated with symptoms, myocardial infarction,3 and systolic click syndrome.4



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