Absent Left Main Coronary Artery with Separate Origin of Left Anterior Descending Artery and Left Circumflex Artery from Left Coronary Sinus

A 49-year-old female presented to the cardiology outpatient clinic with complaints of intermittent episodes of atypical chest pain for the past 6 months. No other significant personal or family history was present. Electrocardiogram (ECG) demonstrated normal sinus rhythm, with no indications of myocardial ischemia. The patient underwent ECG-gated coronary computed tomography angiography (CTA) to rule out obstructive coronary artery disease.

The CTA was negative for obstructive coronary artery disease but revealed a rare anomaly of coronary artery origin. The left main coronary artery (LMCA) segment was absent, and the left anterior descending (LAD) and left circumflex (LCx) arteries were arising directly from the left coronary sinus with separate ostia (Figure 1). The right coronary artery was seen orthotopically arising from the right coronary sinus.

Figure 1

Coronary artery anomalies are rare and can include those of anomalous origin, course, or terminations of any of the epicardial coronary arteries.¹ An absent LMCA segment with separate ostia of the LAD and the LCx arteries is extremely rare. While the anomaly is itself asymptomatic, it may have diagnostic implications. For example, in the presence of this anomaly, selective cannulation of the ostia of either the LAD or LCx arteries during catheter angiography may inadvertently lead to a misdiagnosis of occlusion or atresia of the other coronary artery. The multiplanar reconstruction and volume-rendering capabilities of a coronary CTA allow for accurate delineation of such uncommon anatomical anomalies. This case highlights the importance of coronary CTA in identifying coronary artery anomalies and providing guidance for subsequent endovascular or surgical procedures, if necessary, thereby preventing diagnostic or therapeutic misadventures.