Aortopulmonary fistula with an arch aortic aneurysm is a rare disease that is difficult to diagnose and often presents with sudden, life-threatening heart failure. Here we report a case of aortopulmonary fistula for which we performed a thoracic endovascular aortic repair (TEVAR) with favorable results. A 79-year-old man presented with slurring of speech and body malaise at a neighborhood clinic. A distal arch aortic aneurysm was detected on chest computed tomography (CT) scans, and the patient was referred to our hospital for further management. We identified a saccular aneurysm and the dilated pulmonary artery, with maximum vessel diameters of 80 and 38 mm, respectively, on preoperative chest CT scans. He was diagnosed with an impending aortic rupture and a TEVAR was performed after preparing for a cervical ramification bypass. Intraoperatively, the aortopulmonary fistula had invaded the pulmonary artery, and the shunt created by the invasion was responsible for the sudden exacerbation of heart failure symptoms in the patient. The diameter of the saccular lump did not increase in the postoperative CT and follow-up visits were scheduled for subsequent monitoring. In the absence of significant complications and with improvement of heart failure symptoms, the patient was discharged from our hospital on the 37th postoperative day. He was later transferred to a neighborhood clinic for rehabilitation and subsequently discharged for further recuperation at home in the fifth postoperative month.