Congenital Absence of Left Circumflex Coronary Artery.

Congenital absence of left circumflex artery is a rare congenital anomaly of the coronary arteries. the prevalence of the anomaly in different studies ranges from 0.6% to 1.3%. of these, 80% are benign and asymptomatic and 20% are clinically important. we report a 56-year-old man presented with acute resting chest pain who was diagnosed as having acute anterolateral infarction accompanied by electrocardiographic changes and elevated cardiac enzymes. coronary angiography in different views was conducted, however, no left circumflex artery was found. the territory supplied by the artery had been perfused by the super dominant right coronary artery. therewas no left circumflex coronary artery with anomalous origin. sever stenosis of left anterior ascending artery superimposed to the absent left circumflex artery was presented as acute anterolateral infarction. although absence of the artery is mostly considered as a benign condition, atherosclerotic lesions may be more important in such cases because of diminished compensating mechanisms.