Infected coronary artery aneurysms present high mortality and surgical management is the treatment of choice in most cases. We present a case of a giant infected aneurysm of the mid right coronary artery complicated with purulent pericarditis in an 83-year-old male patient. It is unknown whether the aneurysm or purulent pericarditis preceded. The patient underwent urgent aneurysm resection and coronary artery distal bypass grafting. He died 24 hours after the operation. When purulent pericarditis and ICAA co-exist the riddle of the chicken and the egg becomes apparent.