Mitral Valve Infective Endocarditis Complicated by Aortic Root Abscess: A Rare and Fatal Progression

Infective endocarditis (IE) is a life-threatening condition associated with high morbidity and mortality. Although aortic root abscesses are most commonly associated with aortic valve involvement, this case illustrates that mitral valve endocarditis, particularly in the presence of prosthetic material, can also lead to this rare and fatal complication. Prompt diagnosis and multidisciplinary coordination are critical to improving patient outcomes. We report the case of a 69-year-old male with a history of coronary artery disease status post-coronary artery bypass grafting (CABG) and mitral valve annuloplasty, who was transferred from an outside facility for evaluation of a developing small bowel obstruction. Upon admission, he was found to be in septic shock and was admitted to the intensive care unit (ICU). Empiric broad-spectrum antibiotics were initiated, and blood cultures subsequently grew methicillin-sensitive Staphylococcus aureus (MSSA), prompting de-escalation to targeted therapy with gentamicin and cefazolin. Transthoracic echocardiography revealed vegetations on the mitral annuloplasty ring with concern for extension into the aorto-mitral curtain. Transesophageal echocardiography (TEE) confirmed the presence of an aortic root abscess. Despite confirmation by TEE, cardiac magnetic resonance imaging/computed tomography (MRI/CT) was pursued to further delineate the extent of paravalvular involvement and to guide operative planning. However, surgical intervention was deferred due to persistent hemodynamic instability, multi-organ dysfunction, and an overall prohibitive surgical risk profile. The patient was transferred to a tertiary care center for further management but ultimately expired 36 days after diagnosis. His clinical course was marked by progressive septic shock requiring maximum vasopressor support and acute hypoxic respiratory failure necessitating intubation, underscoring the rapid progression and high lethality of the disease. This case highlights a key learning point, which is that aortic root abscess, though classically associated with aortic valve IE, can occur as a complication of mitral valve endocarditis, particularly in patients with prosthetic devices. Early recognition, careful surgical risk stratification, and appropriate use of advanced imaging are essential. Further studies are needed to define optimal surgical timing, improve risk stratification models, and establish imaging protocols for high-risk patients with complex infective endocarditis.