From Idiopathic Pericardial Hemorrhage to Mycotic Aortic Aneurysm: A Case Report.

Mycotic aneurysms are a dilatation of an artery due to infection of the arterial wall. These can develop in various locations. Common pathogens involved are Streptococcus species and Staphylococcus aureus. Yet, there are no documented cases attributed to Staphylococcus capitis. A 47-year-old woman presented with intermittent chest pain. A diagnosis of acute pericarditis with moderate pericardial effusion was made based on transthoracic echocardiogram (TTE) findings. Evaluations for infection, vasculitis, and autoimmune conditions were negative, at which time the etiology of pericarditis was deemed idiopathic. Computed tomography (CT) showed no aortic findings. She was subsequently started on aspirin and colchicine therapy. Patients symptoms then resolved, and an improved small pericardial effusion was seen on repeat TTE. Three days after discharge, she returned in cardiogenic shock due to a large tamponade. New CT imaging demonstrated a 1.5 cm ascending aorta aneurysm. Pericardiocentesis was deferred due to concern for rapid hemopericardium reaccumulation. Aortogram confirmed CT findings of ascending aorta outpouching above the bifurcation of the right coronary artery. Emergent replacement of the ascending aorta with drainage of pericardial effusion was then performed with intraoperative inspection verifying imaging findings. Blood cultures were negative. However, the surgical specimen grew S. capitis, a rare and slow-growing organism with scarce literature as it pertains to mycotic aortic aneurysms. The patient ultimately recovered from surgery and was discharged on appropriate antibiotics.