BackgroundMitral-aortic intervalvular fibrosa (MAIVF) is a fibrous region connecting the anterior mitral leaflet (AML) and aortic valve. Pseudoaneurysm of the MAIVF is a rare condition that has been reported as a sequela of infective endocarditis (IE) and surgical trauma. Here, we report a case of a ruptured pseudoaneurysm of the MAIVF, along with some literature reviews.Case presentationA 65-year-old man diagnosed with moderate aortic regurgitation five years previously had a fever of unknown origin. He suddenly developed headache and apraxia and was transported to our hospital. He was diagnosed with intracranial hemorrhage and admitted. One week after admission, echocardiography revealed aorto-mitral discontinuity and protrusion with severe regurgitant flow from left ventricular outflow tract to the left atrium. The AML was suspected to have ruptured. However, intraoperatively, the AML structure was preserved. A ruptured pseudoaneurysm of the MAIVF was also observed. Therefore, we successfully performed pseudoaneurysm repair using a bovine pericardial patch, aortic valve replacement, and mitral annuloplasty.ConclusionsP-MAIVF is a rare but potentially life-threatening complication of IE, for which timely diagnosis and prompt appropriate therapeutic intervention are required. In the present case, although neither obvious active IE nor history of previous IE could be identified, healed IE was considered based on the clinical course. The patient had intracranial hemorrhage (ICH) with well-controlled heart failure and underwent elective surgical repair more than one month after the onset of ICH, while the clinical course after the surgical procedure was uneventful.