Aorto-pulmonary artery fistula is an uncommon consequence of chronic thoracic aortic aneurysm and is mostly caused by pressure erosion. This can be aggravated by infection, trauma, surgery and is rarely spontaneous. Cross-sectional imaging in patients with unexplained acute onset high output cardiac failure is a warranted investigation to diagnose fistulous communication between great vessels i.e. aorta and pulmonary arteries, outline the anatomy, diagnose secondary complications and in effectively guiding the management.