Abstract 9480: Persistent MR Reduction With Stabilization of LV Remodeling and Following Chronic Polymer-Mesh Device on Infarcted Myocardium in a Chronic Ischemic MR Model

Abstract

Background: Mitral valve repair with ring annuloplasty for ischemic mitral regurgitation (IMR) is associated with significant recurrent IMR due to continued left ventricular (LV) remodeling as it does not directly address LV and mitral valve tethering. We aimed to assess chronic implantation of novel polymer based mesh device to reduce IMR reduction and reverse LV remodeling. Methods: Five Dorset sheep underwent ligation of second and third circumflex obtuse marginal branches to produce chronic IMR after 8 weeks. Poly-mesh was attached to the infarcted myocardium underlying the papillary muscle with a further 8 weeks follow-up. In addition, chronic IMR was produced in 5 untreated control sheep. IMR severity was assessed by 2D vena contracta width (VCW) and 3D vena contracta area (VCA). LV end-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF) by 2D echo and hemodynamic data were also obtained at each baseline, chronic MR, and chronic poly-mesh stages. Results: In all sheep, after poly-mesh attachment, IMR decreased and this reduction persisted over 8 weeks (VCW 0.42±0.09 to 0.08±0.12cm; VCA 0.13±0.08 to 0.05±0.08cmsq, p<0.01) with significant increase in Emax (1.1±0.5 to 2.9±0.7mmHg/ml, p<0.05). There were no significant changes in LVEF (45.4±6.7 vs 42.6±3.5%, p=NS). Importantly, LV EDV and ESV at chronic poly-mesh stage were reduced compared to the chronic MR stage (EDV 110±15 to 88±18ml, p<0.05; ESV 61±14 to 51±12ml, p=NS) and % increases of both EDV and ESV from chronic MR to chronic poly-mesh stage were significantly lower than those of untreated control sheep (%EDV change -22±11 vs 11±10%, p<0.01; %ESV change -10±14 vs 9±10%, p<0.05) (FIGURE). Conclusions: Chronic follow up after polymer-mesh device attachment shows the stabilization of mitral-LV complex in a chronic IMR model, causing persistent reduction of IMR and preventing continued LV remodeling.