Case Presentation: A 40 year old female presents with intermittent mid-sternal squeezing chest pain, radiating to the left arm since 2 days. She denied any positional change in symptoms or family history of coronary artery disease. Her medical history was significant for hypertension and smoking, and her only home medication was lisinopril. Physical examination was unremarkable. An electrocardiogram showed no acute ST-T wave changes, and serial troponins were negative at 0.01 ng/mL. During an exercise stress echocardiogram, she lasted under 6 minutes due to chest tightness and lightheadedness, with ejection fraction being 55%. Due to her ongoing symptoms, she underwent a coronary angiogram that showed a dominant right coronary artery originating from the left aortic cusp traversing between the aorta and pulmonary artery. This unusual anatomy caused 80% compression stenosis of the vessel, which presumably induced severe crushing chest pain. She eventually underwent single vessel coronary artery bypass to the distal right coronary artery and thereafter her symptoms resolved.

Discussion: Anomalous coronary arteries are found in approximately 1% of the population undergoing coronary angiography, 20% of whom can develop cardiac ischemia and/or sudden cardiac death. Symptomatic right coronary artery (RCA) anomalies are rarer than the left, and arise most frequently from the coronary sinus than any other site. An anomalous RCA originating from the left aortic cusp and traveling inter-arterially has a prevalence of 0.25%. It increases the risk for myocardial ischemia, arrhythmia, syncope and sudden cardiac death. Mechanisms of ischemia include (1) sharp angulation of the RCA at its origin, (2) mechanical compression by aortic expansion, (3) collapse of the vessel’s slit-like origin on exertion, or (4) coronary vasospasm. Treatment involves RCA stenting or surgical correction by bypass graft (most common), artery re-implantation at its proper site, or unroofing.

Conclusions: In the absence of electrocardiographic changes and cardiac biomarkers, anomalous coronary arteries can be a cause for cardiac ischemia. Surgical correction can help resolve symptoms.