Papillary Muscle Dyssynchrony-Mediated Functional Mitral Regurgitation

Objectives This study sought to define interpapillary muscle dyssynchrony as a major contributing factor in functional mitral regurgitation (FMR) and prove the reversibility of FMR by interpapillary muscle resynchronization. Background Mechanistic features of FMR include papillary muscle displacement due to left ventricular remodeling. Intraventricular conduction delay might further augment this condition by introducing interpapillary muscle dyssynchrony. Methods We enrolled 269 chronic heart failure with reduced ejection fraction patients with conduction delay and comprehensively assessed dyssynchrony by complementary echocardiographic techniques covering the entire spectrum of dyssynchrony. Results Patients with severe FMR had markedly increased interpapillary longitudinal dyssynchrony [160 ms (interquartile range [IQR]: 120 to 200 ms])] compared with those with moderate (70 ms [IQR: 40 to 110 ms]), no, or mild FMR (60 ms [IQR: 30 to 100 ms]; p Conclusions Intraventricular dyssynchrony introduces unequal contraction by papillary muscle bearing walls, which has an adverse effect on FMR. Cardiac resynchronization therapy can effectively restore interpapillary balance and thus create a less tented leaflet configuration, resulting in a clinically meaningful reduction of FMR. The restoration of papillary muscle synchronicity in dyssynchrony-mediated FMR translates into a significantly better prognosis.