Acute mitral regurgitation due to ruptured chordae tendineae in a patient with hypertrophic obstructive cardiomyopathy: a case report.

A 63-year-old woman had been followed up for hypertrophic obstructive cardiomyopathy with 85 mmHg of left ventricular outflow tract pressure gradient over 7 years. She was hospitalized because of acute dyspnea and syncope. On admission, echocardiography revealed severe mitral regurgitation with ruptured chordae tendineae at the medial scallop of the posterior mitral leaflet. Mitral valve replacement was successfully performed and her symptoms improved to 28 mmHg of left ventricular outflow tract pressure gradient. In patients with hypertrophic obstructive cardiomyopathy, elevated left ventricular systolic pressure and systolic anterior motion of the mitral leaflets may lead to mucoid degeneration in the chordae tendineae. Rupture of the mitral chordae tendineae should be considered in the differential diagnosis of acutely deteriorated mitral regurgitation in patients with hypertrophic obstructive cardiomyopathy, because this is a rare but critical complication.