Chordal cutting - A new therapeutic approach for ischemic mitral regurgitation

Background-Mitral regurgitation (MR) conveys adverse prognosis in ischemic heart disease. Because such MR is related to increased leaflet tethering by displaced attachments to the papillary muscles (PMs), it is incompletely t reated by annular reduction. We therefore addressed the hypothesis that suc h MR can be reduced by cutting a limited number of critically positioned ch ordae to the leaflet base that most restrict closure but are not required t o prevent prolapse. This was tested in 8 mitral valves: a porcine in vitro pilot with PM displacement and 7 sheep with acute inferobasal infarcts stud ied in vivo with three-dimensional (3D) echo to quantify MR in relation to 3D valve geometry. Methods and Results-In all 8 valves, PM displacement restricted leaflet clo sure, with anterior leaflet angulation at the basal chord insertion, and mi ld-to-moderate MR. Cutting the 2 central basal chordae reversed this withou t prolapse. In vivo, MR increased from 0.8 +/-0.2 to 7.1 +/-0.5 mL/beat aft er infarction and then decreased to 0.9 +/-0.1 mL/beat with chordal cutting (P <0.0001); this paralleled changes in the 3D leaflet area required to co ver the orifice as dictated by chordal tethering (r(2)=0.76). Conclusions-Cutting a minimum number of basal chordae can improve coaptatio n and reduce ischemic MR. Such an approach also suggests the potential for future minimally invasive implementation.