Interarterial course of the left coronary artery

Case contributed by Francis Fortin


Positive cardiac stress testing. Known coronary artery disease (CAD) with prior stenting.

Patient Data

Age: 55 years
Gender: Male

Selected images from left coronary artery catheterization show, on the first image, apparent widening of the proximal left main coronary artery (LMCA) while on other projections it is narrowed.

On dynamic imaging (not shown), there was variable narrowing of the proximal LMCA throughout the cardiac cycle.

The overall appearance is suggestive of an extrinsic compression and therefore coronary CTA was performed.

The LCMA originates from the right coronary sinus. It travels in between the aorta and pulmonary artery, roughly in the plane of the valvular cusps of those vessels, compatible with a "malignant" variant of anomalous course, namely interarterial course of the left coronary artery. There is a roughly 50% non-atherosclerotic stenosis of the proximal LMCA in its interarterial path, due to extrinsic compression.

There is also a mild intra-stent stenosis of the mid- and distal RCA and CAD of the distal LMCA as well as LAD and LCx arteries.

3D reformats from coronary CTA


3D reformat nicely show the origin of the LMCA from the right coronary sinus with interarterial course between the aorta and pulmonary artery, with roughly a 50% stenosis.

Case Discussion

Interarterial course of the left coronary artery is a rare "malignant" variant of coronary artery course, associated with sudden cardiac death.

Case courtesy of Dre Anne Chin, cardiac radiologist at Montreal University Hospital Center (CHUM), Canada.

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