Introduction: Caseous calcification of the mitral an-nulus is a rare variant of chronic degeneration of the mitral valve, involving typically the posterior annulus and has an estimated prevalence of 0.06% in general population, which can reach up to 2.7% in autopsy stu-dies. It is usually considered as a benign condition, but it may cause mitral valve dysfunction, systemic embo-lization or conduction abnormalities. There is no con-sensus regarding the optimal management, but surgery is indicated for severe mitral valve dysfunction, for em-bolic complications or when the diagnosis is uncertain. We report a case of caseous mitral annular calcification presenting with acute myocardial infarction, aiming to reconsider the clinical significance of this condition.
Methods: A 60-year-old female with a history of type 2 diabetes mellitus, hypertension, dyslipidemia, obesity, smoking and coronary artery disease as well as percu-taneous revascularization of the anterior descending artery for anterior myocardial infarction, followed by aortocoronary bypass for in-stent restenosis, was ad-mitted for acute-onset chest pain and dyspnea at rest. Given the clinical status, the rising pattern of cardiac troponins and the ST elevation on the electrocardio-gram tracing, the diagnosis of acute myocardial infarc-tion with ST elevation of the posteroinferior wall was established.
Results: Coronary angiography revealed functional aortocoronary bypass with possible insertion lesion and no significant new coronary stenosis. Transtho-racic and transesophageal echocardiography showed an enlarged left atrium and a 17/21mm hyperecho-genic round mass with filiform vegetation adhered to the posterior leaflet of the mitral valve, causing mild stenosis and moderate to severe regurgitation. Infec-tive endocarditis was ruled out by the negative blood cultures and the absence of clinical criteria. The study was completed with computed tomography and cardiac magnetic resonance imaging that raised a suspicion of caseous calcification. The patient proceeded to surgery for removing the mass and Hancock II bioprosthetic mitral valve replacement, with favourable postopera-tive evolution. Given the macroscopic features of the excised mass, the diagnosis of caseous mitral annular calcification was established.
Conclusions: Despite being considered a benign condi-tion which might be followed-up, there are a number of case reports in the published literature, describing cere-bral embolism associated with caseous mitral annular calcification, possible mechanisms including emboliza-tion of small calcified parts, fistulisation of a caseous necrosis in the lumen of the left ventricle or thrombus formation. In the present case, caseous mitral annular calcification was associated with acute myocardial in-farction with nonobstructive coronary arteries. Becau-se of the uncertain diagnosis, the embolic potential of the mass and the severe mitral dysfunction, a surgical management was chosen, with favourable postoperati-ve evolution.