Interarterial course of the left coronary artery

The interarterial course of the left coronary artery, also known as the malignant course of the left coronary artery, is defined as the origin of the left main or left anterior descending coronary artery from the right coronary sinus of Valsalva with a course between the ascending aorta and the pulmonary artery. This is called a malignant variant because of the marked increased risk for myocardial ischemia or sudden cardiac death.

The incidence of inter-arterial course of the left coronary artery is estimated at ~1.3% of coronary anomalies, and is feared most because of association with myocardial ischaemia and sudden death in young people.

In many cases of interarterial course of the left coronary artery, other associated anomalies such as slit-like orifice, stenotic ostium, a sharp, acute angle of takeoff, and an intramural aortic segment are also present.

Different theories have been postulated as a cause of sudden death in these patients:

  • most accepted theory is the higher incidence of occlusion of the ostium secondary to a more slit-like orifice
  • occlusion during physical activity due to compression between the major arteries

An intramural segment within the aortic wall (not to be confused with myocardial bridging) further increases the risk of sudden death.

Because the exact association between interarterial course of the left coronary artery and sudden death is still under debate and not well established, surgical repair mostly depends on other factors such as the presence of symptoms and whether other causes can or cannot be found in a patient with chest pain. Corrective surgery (if the intramural portion is present) is performed by "unroofing" the intramural portion of the anomalous coronary artery resulting in a larger orifice.

Congenital coronary artery anomalies
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Article information

rID: 39470
System: Cardiac, Vascular
Section: Anatomy
Synonyms or Alternate Spellings:
  • Inter-arterial course of the left coronary artery
  • Malignant course of the left coronary artery

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