Anomalous coronary arteries may have a so-called benign (asymptomatic without risk of decreased blood flow) or a malignant (potentially symptomatic with risk of decreased blood flow, ischemia, and sudden death) course. In most cases, a vessel running between the aorta and the pulmonary artery has a malignant course. Vessels running in front of the pulmonary artery (pre-pulmonic) or behind the aorta (retroaortic) are considered to have a benign course.