Left Internal Mammary Artery-to-Pulmonary Vein Fistula: A Rare Cause of Unstable Angina

The incidence of acquired left internal mammary artery-to-pulmonary vein fistulas has been increasing in the last few decades. This has been attributed to the increase in coronary artery bypass surgery (CABG). The most commonly reported symptoms are angina and dyspnea. The timing of the presentation varies widely from a few months to several years after CABG. Medical management is the treatment of choice and usually controls the symptoms in most patients. Percutaneous intervention is, however, indicated when medical therapy fails. In this case report, a 72-year-old man with a history of CABG presented with progressively worsening chest pain and dyspnea. Troponin was negative and the electrocardiogram showed no acute ischemic changes. He was found to have left internal mammary artery-to-pulmonary vein fistula on coronary angiogram. His symptoms improved upon intensifications of his guideline-directed therapy for coronary artery disease. This represents an unusual cause of unstable angina.