Teaching Case

The patient presented with right-sided chest pain and shortness of breath. His labs were notable for an elevated troponin (3.16 ng/mL). EKG demonstrated first-degree heart block with a non-specific intraventricular conduction delay and treatment for non-ST elevation myocardial infarction was initiated.

Transthoracic echocardiography was performed (Fig. 1) and revealed a hyperdynamic left ventricle with an ejection fraction of 76% with a severely dilated left atrium, severe mitral annular calcification, moderate mitral regurgitation, and severe pulmonary hypertension. In addition, a round, 3 cm hyperechoic mass in the basal interventricular septum extended into the basal right ventricle just above the septal leaflet of the tricuspid valve.
CT angiography was later performed and demonstrated heavy calcification of the mitral annulus with myxomatous degeneration and calcification extending into the moderator band of the right ventricle, aortic valve, and interventricular septum (Fig. 2a-c) along with advanced three-vessel coronary atherosclerosis. Subsequently, left heart catheterization was performed with percutaneous coronary intervention (PCI) of the second obtuse marginal branch with a 2.5 x 12 mm drug eluting stent due to severe stenosis and evidence of plaque rupture. The presence of extensive intra-myocardial calcification was confirmed on fluroscopy (Fig. 3a-b).

Mitral annular calcification (MAC) is a degenerative disease that is often seen in the elderly that forms from the breakdown of the cardiac fibrous framework. Caseous calcification is a rare variant of MAC that presents as a soft, periannular calcification that is a mixture of calcium, cholesterol and fatty acids. [1] The pathogenesis of caseous calcification is not well understood. Prior studies have shown that atherosclerotic lesions in other vascular beds are related to calcification of the mitral annulus, and a high prevalence of caseous calcification in patients with end stage renal disease may indicate that altered calcium-phosphate metabolism may contribute to the formation of caseous calcification [2]. Imaging along with pathological findings help distinguish this disease from other processes.

The modality of choice that is most often utilized to identify caseous calcification is usually echocardiography. On examination, the mass is seen as less echoic than normal mitral annular calcification, and a central, relatively hyopechoic zone is identified without acoustic shadowing [1]. Due to poor image quality, other imaging modalities were used as prior studies have shown that CT can help verify a diagnosis of caseous calcification, and CT angiography demonstrated that extensive calcification with myxomatous degeneration led to a thickened mitral annulus with decreased mitral excursion [3]. Microscopic examination of the mass also helped confirm the diagnosis as pathologic findings included amorphous eosinophilic material, acellular debris, diffuse calcification and fat necrosis with mixed inflammatory infiltrate surrounding the mass, all of which are classic characteristics of caseous calcification [1]. Intracardiac masses such as this are often confused for other disease processes such as myxomas, abscesses and vegetations. Myxomas tend to be variable in shape, highly vascular, and they possess less calcification on the outer borders, and abscesses have a very similar presentation to caseous calcification except they also tend to have a vascular component with a lack of calcifications [4].

Caseous calcification is generally regarded as a benign process that is discovered most often as an incidental finding, but in rare cases, such as this one, malignant manifestations can result. This patient’s calcification was sizeable enough to result in mitral stenosis. This mitral stenosis along with other comorbidities such as CKD most likely led to the patient’s final cardiovascular decompensation. Hopefully, with the use of multiple imaging platforms coupled with pathologic examination, caseous calcification can be discovered in future cases to avoid unwanted adverse events.