Giant coronary fistula aneurysm presenting as a progressing left-sided asymptomatic mediastinal mass with systolic dominant Doppler flow: a case report

BACKGROUND: Cases of giant coronary artery aneurysms (GCAAs) associated with coronary fistula are rarely reported, and they present with various symptoms, including coronary steal syndrome. We report an uncommon case of an asymptomatic giant coronary fistula aneurysm presenting as a progressing left-sided mediastinal mass that has been tracked for years. CASE SUMMARY: A 67-year-old healthy asymptomatic woman was referred to our hospital because of an abnormal shadow on her chest radiography revealing a left-sided mediastinal mass that had progressed in size over the past 4 years. Computed tomography revealed mass progression from 4 to 5 cm in diameter within 2 years. Coronary computed tomography and coronary angiography identified a GCAAs in a coronary fistula originating in the left anterior descending artery and draining into the main pulmonary artery. Transthoracic Doppler echocardiography revealed a unique systolic dominant flow. She underwent coronary artery aneurysmectomy and fistula ligation. The patient has been in good health without any events for 10 months since her discharge. DISCUSSION: A GCAAs in a coronary fistula can present as an asymptomatic left-sided mediastinal mass that has progressed in size for years in older adults. Echocardiography can provide clues of the steal phenomenon in coronary artery fistula. A close investigation of mediastinal abnormalities can facilitate the detection of coronary aneurysms.