Regression of mitral regurgitation after cardiac resynchronization therapy in an adult with preserved left ventricular function and right ventricular pacing.

We report the case of a 60-year-old patient with preserved ventricular function and no organic mitral leaflet disease implanted with a dual-chamber pacemaker. Right ventricular pacing induced a major ventricular dyssynchrony, a severe mitral regurgitation, and symptoms of congestive heart failure. Upgrading to a biventricular device was associated with a decrease in the symptoms, the ventricular dyssynchrony, and the mitral regurgitation.