Reversible severe mitral regurgitation caused by systolic anterior motion of the mitral valve in the absence of left ventricular hypertrophy: A case report.

A 67-year-old woman with exertional dyspnea was referred to our hospital. Transthoracic echocardiography revealed severe mitral regurgitation and significant left ventricular (LV) outflow tract obstruction due to prominent systolic anterior motion (SAM) of the mitral valve without LV hypertrophy. Oral bisoprolol remarkably attenuated SAM. Two- or three-dimensional echocardiographic analysis demonstrated the elongation of anterior and posterior mitral leaflets and interventricular septum (IVS) bulging due to narrow aorto-mitral angle. In the present case, elongation of mitral leaflet and hyperkinetic motion of left ventricle, and IVS bulging due to narrow aorto-mitral angle possibly play important roles in the development of SAM. <Learning objective: Mitral regurgitation due to systolic anterior motion (SAM) can be dramatically improved by beta-blocker therapy. Although the precise mechanism of SAM has not been fully elucidated, structural changes of mitral apparatus (elongation of mitral leaflet and papillary muscle displacement), and structural or functional features of left ventricle (hyperkinetic motion, small ventricle, interventricular septum bulging, narrow aorto-mitral angle) possibly play important roles in the development of SAM.>.