Abstract
BACKGROUND: A coronary artery fistula (CAF) is an abnormal connection between a coronary artery and another cardiovascular lumen. CASE SUMMARY: The authors report a case of a large CAF originating from the left circumflex (LCX) and draining into the lower segment of the superior vena cava, resulting a shunt ratio of 1.3. The patient also had a severe bicuspid aortic valve insufficiency and ventricular dilatation yet remained asymptomatic. A single surgical procedure was performed to address both the fistula and the valvular pathology. Postoperative computed tomography angiography revealed a reduced LCX diameter proximal to the fistula site, with evidence of smooth plaque/mild thrombosis in the LCX walls. In addition, the coronary calcium score was high. The patient was on anticoagulant and statins, with low-density lipoprotein level of 1.3 mmol/L. DISCUSSION: A CAF between the LCX and superior vena cava is exceedingly rare, with limited cases reported and no established management guidelines, complicating clinical decision-making.