Left Circumflex Artery as a Terminal Extension of Right Coronary Artery.

To the Editor: Coronary artery anomalies are usually detected incidentally during diagnostic coronary angiography or computed tomography examinations. The failure to visualize a coronary artery in its usual location may be misinterpreted as a total occlusion.

A 58-year-old man was admitted to our department because of shortness of breath and palpitation. His medical history revealed hypertension and cigarette smoking. Physical examination was unremarkable. Electrocardiography showed nonspecific ST and T wave abnormalities on V4–V6 derivations. Transthoracic echocardiography demonstrated left ventricular diastolic dysfunction (Grade 1) and mild mitral regurgitation. Myocardial perfusion imaging was performed to evaluate inducible ischemia, and showed small ischemic area (4%) in mid-basal inferior wall. Diagnostic coronary angiography revealed a normal left anterior descending artery (LAD), but the left circumflex artery (LCA) could not be visualized in its normal location [Figure 1a]. On selective right coronary angiography, LCA was visualized as a terminal extension of the right coronary artery (RCA) [Figure 1b]. To clarify this coronary anomaly, we performed computed tomographic angiography, which showed the same pathology [Figure 2].

Figure 1

Left coronary angiography showed a normal left anterior descending artery, but the left circumflex artery (LCA) could not be visualized in its normal location (a); in right coronary angiography, the LCA was visualized as a terminal extension of the right coronary artery (b).

Figure 2

Computed tomographic angiography revealed the absence of the left circumflex artery and a superdominant right coronary artery with large posterolateral branches.

Isolated coronary anomalies are rare abnormalities, and their prevalence is less than 1.3%.[1] The most common coronary anomaly is separate origin of LAD and LCA from the left sinus of the valsalva. The LCA arising from the right sinus of valsalva is other anomaly involving the origin of LCA.[2] LCA as an extension of RCA is a very rare anomaly, being reported in only few cases in the literature.[34] Coronary artery anomalies can be divided into benign and malignant forms. Benign abnormalities often remain asymptomatic because they are hemodynamically insignificant. Benign isolated coronary anomalies are often incidental findings during diagnostic imaging modalities and autopsies. To avoid longer procedure time, and more radiation exposure, cardiologist, and cardiac surgeons should be aware of coronary artery anomalies.