This study assessed the mechanism of acute mitral regurgitation following balloon mitral valvuloplasty for the treatment of symptomatic mitral stenosis. We studied 25 patients who required mitral valve replacement for severe mitral regurgitation following balloon mitral valvuloplasty. All the mitral valves studied had features of severe mitral stenosis. Radial tear of the mitral leaflet was responsible for mitral regurgitation in 18 (72%) cases. Of these, 16 involved the anterior mitral leaflet and in 2 cases the posterior mitral leaflet was torn. Three patients (12%) had chordal rupture, whereas in 4 (16%) patients pseudo-orifices were formed. All the excised mitral valves showed significant subvalvular deformity which was underestimated in prevalvuloplasty echocardiography. No other factor was found to be associated with disruption of the valve. Hence, we conclude that cusp deformity and subvalvular pathology are responsible for faulty transmission of forces and improper engagement of the balloon, resulting in disruption of the valvular apparatus. The incidence of severe mitral regurgitation following balloon mitral valvuloplasty might be decreased by appropriate prevalvuloplasty assessment and patient selection.
Letter: Posterior mitral leaflet motion in severe mitral stenosis.