Serial Assessment of Liquefaction Necrosis of Mitral Annular Calcification by Echocardiography and Multislice Computed Tomography
An asymptomatic 54-year-old man, who had been on hemodialysis for 11 years because of chronic renal failure caused by chronic glomerulonephritis, was observed in our hospital. In November 2002, an aortic valve replacement was performed because of severe aortic stenosis. Preoperative echocardiography demonstrated mitral annular calcification (MAC) at the base of the posterior mitral annulus (Figure, A). Computed tomography of the heart also identified the MAC (Figure, B). In November 2004, follow-up echocardiography revealed enlargement of the MAC, which was detected as a spherical dense echogenic calcified mass (36×21 mm) with a central echolucent area (Figure, C). Trivial mitral regurgitation was observed. Electrocardiographic gated cardiac multislice computed tomography confirmed that the mass had a high density but also contained a low-density area that was thought to be soft tissue (Figure, D). Multislice computed tomography coronary angiography showed that the mass had no feeding artery. These findings suggested that this mass was a liquefaction necrosis of the MAC. Additional treatment was not performed because liquefaction necrosis of MAC usually has a benign prognosis. After 11 months, echocardiography and multislice computed tomography revealed that the size of the mass was reduced (16×6 mm), especially in the central liquefaction region (Figure, E and F). Doppler echocardiography also revealed moderate mitral regurgitation attributable to incomplete cooptation. Although the pathogenesis of MAC in chronic renal failure is related to calcium–phosphorus homeostasis, the levels of total serum calcium, serum phosphorus, and calcium–phosphorus product were not changed significantly during the observation period. These findings clearly demonstrated that liquefaction necrosis was a reversible form of MAC. Because mitral regurgitation with various grades could have been caused by the varying size of the MAC, further follow-up study was necessary for this case. Serial assessment was important in this particular disease.