Calcific extension towards the mitral valve causes non-rheumatic mitral stenosis in degenerative aortic stenosis: real-time 3D transoesophageal echocardiography study

OBJECTIVE Mitral annular/leaflet calcification (MALC) is frequently observed in patients with degenerative aortic stenosis (AS). However, the impact of MALC on mitral valve function has not been established. We aimed to investigate whether MALC reduces mitral annular area and restricts leaflet opening, resulting in non-rheumatic mitral stenosis. METHODS Real-time three-dimensional transoesophageal images of the mitral valve were acquired in 101 patients with degenerative AS and 26 control participants. The outer and inner borders of the mitral annular area (MAA) and the maximal leaflet opening angle were measured at early diastole. The mitral valve area (MVA) was calculated as the left ventricular stroke volume divided by the velocity time integral of the transmitral flow velocity. RESULTS Although the outer MAA was significantly larger in patients with AS compared to control participants (8.2±1.3 vs 7.3±0.9 cm(2), p<0.001), the inner MAA was significantly smaller (4.5±1.1 vs 5.9±0.9 cm(2), p<0.001), resulting in an average decrease of 45% in the effective MAA. The maximal anterior and posterior leaflet opening angle was also significantly smaller in patients with AS (64±10 vs 72±8°, p<0.001, 71±12 vs 87±7°, p<0.001). Thus, MVA was significantly smaller in patients with AS (2.5±1.0 vs 3.8±0.8 cm(2), p<0.001). Twenty-four (24%) patients with AS showed MVA <1.5 cm(2). Multivariate regression analysis including parameters for mitral valve geometry revealed that a decrease in effective MAA and a reduced posterior leaflet opening angle were independent predictors for MVA. CONCLUSIONS Calcific extension to the mitral valve in patients with AS reduced effective MAA and the leaflet opening, resulting in a significant non-rheumatic mitral stenosis in one-fourth of the patients.