What complication of radiofrequency ablation for atrial fibrillation is responsible for this head imaging? A middle-aged patient was admitted to intensive care for a coma (Glasgow Coma Scale score, 3) and fever (temperature, 39.3 °C) 4 weeks after percutaneous radiofrequency ablation for persistent atrial fibrillation. A brain computed tomography scan revealed the presence of air in the brain, consistent with bilateral supratentorial and infratentorial air emboli in the cerebral vessels and parenchyma (Figure). A diagnosis of left atrioesophageal fistula responsible for the massive cerebral air emboli was sustained. Blood cultures grew Streptococcus salivarius and Candida albicans, consistent with an upper digestive tract origin. Diffuse cerebral edema developed, and brain death was declared on day 3 after intensive care unit admission.