Efficacy of the Edge-to-Edge Repair in the Setting of a Dilated Ventricle: An In Vitro Study

Background The edge-to-edge repair to correct mitral regurgitation (MR) has shown substandard results in cases of ischemic MR or dilated cardiomyopathy. Methods Ten porcine mitral valves were investigated in a left heart simulator (120 mm Hg, 5 L/min). Pathologic conditions of a dilated ventricle were simulated by using an annular model capable of three levels of dilation (normal, 56%, and 120%) and by displacing papillary muscles (PMs) 10 mm in the apical, lateral, and posterior directions. The edge-to-edge repair was performed; a central stitch was investigated for symmetric and asymmetric PM displacements, and a paracommissural stitch was investigated for asymmetric PM displacements. Left ventricular pressure and mitral flow rate were monitored, and regurgitation fraction was calculated from the mitral flow curve. Results Under symmetric PM displacement, the repair reduced MR by 5.1% at dilation level one and by 9.1% at dilation level two. The repair decreased MR by 10.9% (dilation level two) after asymmetric displacement of the anterior-lateral PM, and by 5.4% (dilation level one) and 7.9% (dilation level two) after asymmetric displacement of the posterior-medial PM. The edge-to-edge repair reduced (p < 0.05) MR owing to annular dilation; however, it was unable to completely eliminate the MR. The repair did not significantly reduce MR caused by PM displacement, regardless of the displacement geometry. Stitch location did not affect repair efficacy. Conclusions The edge-to-edge repair is not an effective procedure in correcting MR associated with PM displacement, although it is able to partially reduce MR caused by annular dilation.