A 58-year-old Japanese woman was admitted to our hospital because of chest
pain. A continuous murmur was detected at the left parasternal area. Electr
ocardiogram showed ST elevation in leads V-2, V-3 and V-4. Chest computed t
omography and echocardiography demonstrated pericardial effusion and a larg
e mass which was adjacent to the pulmonary artery. An abnormal blood flow w
as detected in the mass by Doppler echocardiography. Coronary angiography c
onfirmed that the mass was a giant aneurysm of coronary arteriovenous fistu
la arising from both the left and right coronary arteries. This patient had
no symptoms until rupture of the fistula. Rupture of a coronary arterioven
ous fistula is very rare but can be a cause of chest pain and pericardial e
ffusion.