Myocardial infarction induced by caseous mitral annular calcification: a case report

Caseous mitral annular calcification (CMAC) is a rare variant of mitral annular calcification. Symptoms can be related to mitral valvular dysfunction, arterial embolization, and transient aortic outflow tract obstruction. CMAC usually affects the posterior fibrous mitral annulus and is commonly diagnosed in elderly patients with a history of hypertension, dyslipidaemia, and renal failure.

A 68-year-old patient was transferred to our department for late presenting acute myocardial infarction and acute heart failure. Coronary angiography revealed a significant extrinsic compression of the circumflex artery. Transthoracic echocardiography revealed an ovoid calcified mass of 3.6 cm × 2 cm originating from the posterior mitral annulus causing moderate mitral stenosis as well as akinesia of the inferolateral wall, reduced left ventricle ejection fraction (35%), and a low-flow low-gradient severe aortic stenosis. Cardiac computed tomography scan confirmed the presence of a large calcified mass, inserted to the posterior mitral annulus evocating caseous necrosis. The patient underwent a double valve replacement with implantation of both aortic and mitral bioprostheses. Histopathology of the excised mass revealed a chronic mitral valve fibrocalcification with aseptic necrosis, consistent with a caseous calcification of the posterior mitral annulus.

Extrinsic coronary artery compression is a rare disease entity. We report a rather peculiar cause of extrinsic artery compression: CMAC inducing significant mitral stenosis and compressing the circumflex artery leading to myocardial infarction. To the best of our knowledge, this is the first case of extrinsic artery compression caused by CMAC.