Eisenmenger syndrome is a late complication of untreated congenital heart disease associated with left to right shunt, that can prompt in situ pulmonary thrombosis. Herein the case of a 41 year old man with suspected pulmonary embolism, where an atrial septal defect lead to Eisenmenger Syndrome, is presented. Only lung transplantation and surgical defect closure revealed to be the optimal treatment.