Mid-systolic click and echocardiographic evidence of mitral valve prolapse during electrical pacing.

A mid-systolic click was present in a patient during three years of follow-up after implantation of a permanent transvenous pacemaker. Echocardiography revealed posterior motion of the anterior leaflet which resembled mitral valve prolapse. Both the click and echocardiographic evidence of prolapse disappeared simultaneously with resumption of sinus rhythm and during supraventricular tachyarrhythmias. Wtih spontaneous change in the position of the electrode three years after initial implantation, both the click and the posterior motion of the mitral valve disappeared. The association of mitral valve prolapse with electrical pacing is most unusual and appears to have a distinct pathophysiological mechanism.