The congenital absence of the left circumflex artery (LCx) is a very rare congenital anomaly of coronary arteries, but it is benign. Currently, the best modality for the diagnosis of coronary anomalies is computed tomography coronary angiography (CTCA). We report a case of congenitally absent LCx with an atypical chest pain.
Congenital anomalies of coronary arteries are a group of disease, which is infrequently found. Their prevalence has been reported to range from 0.6% to 1.3% [
A 52-year-old Thai man presented with acute chest tightness and palpitation while rubber farming for 1 week. He had a history of hypertension and heavy smoking for 10 years. He was admitted at a local hospital, and the results of the complete blood count and lipid profile showed within normal limits. His electrocardiogram showed a normal sinus rhythm with Wolff-Parkinson-White syndrome, and his clinical signs did not improve, so he was referred to our hospital. His clinical condition was suspected to be due to coronary arterial disease by a cardiologist. However, his exercise stress test was inconclusive, so he was further investigated by CTCA.
The 64-slice CTCA findings showed no calcified coronary artery walls, and the calcium score was zero. A completely absent LCx was observed, which was associated with multiple enlarged diagonal branches of the left anterior descending artery (LAD) to supply the lateral wall of the left ventricle (Figure
Top view three-dimensional computed tomography scan shows absent left circumflex artery in the atrioventricular groove (arrowed heads) with single left anterior descending artery (thick arrows) and prominent diagonal branches (thin arrows).
Inferior view of three-dimensional computed tomography scan shows superdominant right coronary artery (large arrow) to supply posterior wall (small arrow).
A maximal intensity projection image shows overall course of superdominant right coronary artery (arrow).
In the past, congenital anomalies of coronary arteries were incidentally diagnosed by conventional coronary angiogram; however, this is an invasive technique. Selective angiogram may find it difficult to determine the origin of an artery in the case of anomalous arterial origin. Moreover, its interpretation may also be difficult in cases of anomalous course and origin. For example, in our case, it may be difficult to differentiate between the congenital absence and total occlusion diagnoses based on the angiogram findings. Today, a more advanced technology, CTCA, is better for detecting congenital anomalies, because it is widely available, noninvasive and is characterized by a rapid acquisition of results [
The congenitally absent LCx is an extremely rare anomaly of coronary arteries; a small number of cases have been reported. Its incidence was reported by Yamanaka and Hobbs to have a frequency of only 0.003% in patients undergoing coronary angiography [
The congenital absence of the LCx results from the failure of LCx development in the left atrioventricular groove. However, some authors believe that this condition is not a real congenital absent anomaly so it is defined as anomalous origin of the LCx from distal RCA [
The imaging findings of congenitally absent LCx show no demonstrable LCx in the left atrioventricular groove. This finding is associated with the superdominant RCA continuing into the LCx territory and prominent multiple diagonal branches from the LAD to supply the lateral wall of the left ventricle, as seen in many literatures [
In conclusion, the congenital absence of the LCx is an extremely rare anomaly of coronary arteries. CTCA is the best modality to detect congenital coronary anomalies because it is fast, safe, and highly accurate.
None of the authors have any financial relationships with any commercial identity used in this paper.
The authors thank Edmond Subashi of the International Affairs of the Faculty of Medicine, Prince of Songkla University for editing.