Considerations in caseous calcification of the mitral annulus: a case report

Background: Caseous calcification of the mitral annulus is an extremely rare variant of mitral annulus calcification occurring in <1% of cases. The degeneration of caseous masses could act as a source of embolic strokes and a nidus for infective endocarditis (IE). Case summary: A man in his sixties presented with transient left arm weakness. His history was pertinent for bioprosthetic aortic valve replacement secondary to endocarditis and recent pneumococcal pneumonia complicated by empyema and bacteraemia. He was still on intravenous antibiotics when he presented. Evaluation including magnetic resonance imaging of the brain, transoesophageal echocardiography, and computed tomography (CT) of the chest revealed multifocal embolic strokes, degenerative bioprosthetic aortic valve dysfunction, mitral annular calcification with mobile calcific masses, and persistent empyema. 18F-fluorodeoxyglucose-positron emission tomography-CT showed indeterminate activity across a portion of the posterior mitral leaflet and no activity on the bioprosthetic aortic valve. The patient was deemed high risk for surgery and was treated with 6-week course of antibiotics both for the empyema and the possible IE of the native mitral valve. Repeat echocardiography 40 days later showed stable mitral masses. At 4 months of follow up, the patient had no evidence of recurrent clinical strokes. Discussion: Caseous calcification of the mitral annulus is a rare but an increasingly recognized predisposing factor for embolic strokes and IE. Treatment ideally involves surgical resection of the calcified masses in such cases.