Anomalous left anterior descending artery diagnosed on pulmonary artery computed tomography

Typically, the left anterior descending artery (LAD) and left circumflex artery (LCX) arise from the left main coronary artery. However, uncommon coronary anomalies may be found in clinical practice. This case presents with a rare finding where the LAD originates from the right coronary artery (RCA) separately from the LCX and takes an interarterial pathway to reach its perfusion territory. A 49-year-old Hispanic female with hypertension and diabetes mellitus presented to the emergency department with a 7-day history of chest pain. She denied nausea, diaphoresis, syncope, or other symptoms. A grade 3 out of 6 systolic murmur was noted on physical examination. Computed tomography of the pulmonary arteries (CTPA) revealed that the patient had no left main coronary artery. The patient's LAD arose from the proximal RCA and took an inter-arterial course. Subsequent coronary catheterization showed no stenosis of the coronary arterial system. The patient's chest pain subsided during the course of her admission and she was deemed stable for discharge with close cardiology follow up. In general, coronary artery anomalies are an uncommon finding in clinical practice. However, it is important to realize the different pathways of coronary artery anomalies because those with the inter-arterial subtype, such as our patient, may result in sudden cardiac death. All cases of clinically suspected inter-arterial coronary artery anomalies are recommended to undergo imaging studies to help visualize anatomic features as a guide for further management. This case represents the first reported diagnosis of this type of anomalous coronary artery on CTPA.