Coronary artery fistula (CAF) is a relatively rare disease, many of which are asymptomatic and are not indicated for surgery. However, CAF's patients with angina, heart failure due to shunt, and fistula hemangiomas are usually indicated for surgical treatment. A 49-year-old woman with severe congestive heart failure was found to have a fistula from the main trunk of the left coronary artery to the left atrium, and a fistula aneurysm. This patient had heart failure due to shunt blood flow, and also had a fistula aneurysm, so surgical treatment was indicated. During surgery, the fistula aneurysm was incised and the origin and opening of the fistula were closed without any problems. The postoperative course is good, and as of three years after the operation, the patient is being followed up at an outpatient clinic without recurrence of shunt flow and heart failure.